There aren't very many Spirit Tracks for us to travel on in the Snow Realm as of yet, so our first destination is Anouki Village, which is located on the top portion of the track loop we're approaching. While we're there, the person we need to talk to is Honcho the village leader, who is located in the center house at the north end of the village. Just south of his house near a couple of stairs, there's a rocket-shaped statue that hums out a color-coded tune. Use your Spirit Flute to learn that tune. It is the Song of Discovery, and the statue will blast off while a treasure chest pops up, giving you Red Potion that can restore six hearts.
Now go into Honcho's house and talk with him about the Snow Sanctuary, and he will tell you that not only are the tracks gone, but also there are monsters popping up everywhere, putting the Anoukis in a real bind. He needs Link's help to pair up members of the village so they can best defend themselves against the monsters. Agree to help, and Honcho will tell you to talk to the villagers and find out from what they tell you about their likes and dislikes who would be the best pairs, with only Honcho being the one who isn't very particular who he's paired up with. Once you get all the information from the Anoukis, talk to Honcho again and he will show you a diagram that lets you draw a line between the two Anoukis best suited for each other. Present the final result to Honcho and, if he finds the pairings agreeable, he will give you 20 rupees as a reward. He will now tell you that the tunnel of the track leading to the Snow Sanctuary is still intact, but nobody's used it since a "ginormous monster" has moved into it a few years back. Mark the location of the tunnel that he shows you on the map, then head back to the station and set course for the tunnel.
Once you're inside the tunnel, however, the "ginormous monster" drops down from the ceiling and starts chasing after the train. This is the Rocktite, and its only vulnerable spot is its eye which is inside his "mouth". As the train continues on autopilot, focus on blasting the Rocktite's eye with your cannon, trying to keep it from getting close enough to jump onto the train and crush it. The first several times you'll be able to stop the monster for a bit, but you won't be able to destroy it. Watch during those lulls for its eye to reappear, and then start blasting away when it comes chasing after you again. Eventually you'll be able to destroy the Rocktite before it destroys you.
Immediately after coming out of the tunnel, the train will stop at the Snow Sanctuary station. To the north of the station there's a single house where an Anouki runs a shop. One item he's selling, a Heart Container, is worth more than we can afford to hold in our wallets at this point -- 2000 rupees! (You can come back for it later when you've collected more rupees by cashing in various treasures that you have found, though.) However, he does have a Purple Potion, which is able to restore eight hearts, that we can buy for 150 rupees.
On our way to the sanctuary, Link has to deal with White Wolfos and Ice Chuchus. White Wolfos like to circle around you before they charge and attack, so wait until they charge before giving them a good swipe of your sword (a Spin Attack will kill them in one strike). Ice Chuchus freeze Link upon contact, requiring a quick rub to break him free. To deal with Ice Chuchus, use the Whirlwind to blow them back and to stun them, then slay them with the sword.
Once we enter the door on the north side of the village, there's a timed puzzle that requires running around a group of statues without them looking at Link doing so before the door closes after pushing a floor button. You may want to check out which direction each of the statues are facing before attempting to solve the puzzle. Past the door we can talk to Steem who will teach us the Lokomo Song that we need to play as a duet in order to unlock a whole lot of Spirit Tracks in the Snow Realm.
Getting to the Snow Temple
However, we have a new problem to deal with, as Steem warns us -- there are terrible blizzards across the tracks that take you to the Snow Temple that will prevent you from reaching it. Try as you might, you'll just be transported back to where you started if you make the attempt to cross those tracks. Our next course of action is to return to Anouki Village (fortunately there's a new track that leads us back to the village so we don't have to go through the tunnel again) and talk to Honcho about dealing with the blizzard problem. Honcho will tell you about a train enthusiast named Ferrus who might be able to tell you how to get through the blizzard. Ferrus is located at Wellspring Station, so that's where we need to go to find him.
Plot your course toward the B-shaped loop on the eastern part of the Snow Realm (which is where Wellspring Station is near) and get the train rolling. Along the way we'll have snowmen that will launch their heads at you like cannons; these require two shots to be destroyed. Once you reach Wellspring Station, you'll notice that Ferrus isn't home (his house seems to be the only one that exists here), but he left behind a note on a table that shows where he's possibly gone to to take snapshots of trains. (There's also a note on the wall which has his explanations of what those archways really are!) Match the locations on the note to locations on the map (they're all in the B-shaped loop) and mark them before heading off for those locations, watching out for the Dark Train that patrols the lower part of the B-loop. A clue that you're getting near Ferrus is that you'll hear camera flashes going off, so get ready to pull to a stop when you hear them. Ferrus will be so excited to see the Spirit Train, he will be eager to help you out by giving you a dusty map. Blow off the dust and you'll see the trail he's marked off that will help you get through the blizzard.
Copy the trail of the dusty map to your map, then get the train rolling and set a course along the same trail. You'll have little problem getting through it now, besides dealing with the head-throwing snowmen along the way.