Although the game told you that you needed "more experience" to ride the train, actually you had to complete the correct quests.
In order to reach the Snowy Mountains you must first complete the phase "Train Regain" in the quest series "Forts and Courts".
Once the phase is completed you will click on the train. This will take to to a new screen showing a map with the following destinations: "Hidden Canyon," "Snowy Mountain," "El Dorado," and "Coming Soon." "Coming Soon" is a place-holder for a future update.
The following quests must be done in order. You probably have finished some of these quests but have one available now.
- Welcome Tasks
- Introductory Series
- Lookin' Fer Answers
- Our Journey Begins
- Ado Adobe
- Colossal Concerns
- Horsin' Around
- Mystery Egg
- City Planning
- Sculpture and Horticulture
- Forts and Courts
Quests involving the Snowy Mountain also have a Hidden Canyon component. You will begin a quest building in the Canyon, collect items from the Mountain, and use those items to finish the Canyon building. Phases that should be done at the Mountain have a blue-white icon when you are not viewing the tasks. When viewing the tasks, you will see the same wooden background as any other quest phase.
While working at the Mountain, you will use your Mountain helper. You may leave the area while you wait.