Once you complete the An Alien Concept: Weather Machine quest you are able to build the snow park, the location of the snow park can be found on the town map on this post.
This is a birds eye view of the snow park:
Snowballs
There are two snowball walls at the snow park so your preteen, teen, adult and senior sims can have a snowball fight for 2 hours
NOTE: you need two sims to be able to do this action
Ice Hockey Rink
At the ice hockey rink your sims can play hockey or go ice skating
Hockey Net- click on the hockey net and your preteens, teens and adults can play hockey
NOTE: this is not a hobby and only one sim can use a hockey net at one time
Figure Skating- click on the dark grey circles on the rink to do the figure skating hobby to unlock the ski lift key
Preteens, teens and adults can partake in this hobby and 4 sims can do it at one time at the snow park
Ski Lift
Once you complete the figure skating hobby for the first time you will be able to access the ski lift to toboggan and snowboard
Toboggan- preteens, teens and adults can use:
Snowboards: preteens, teens and adults can use:
Log Cabin
In the log cabin there is a bar, kitchen, toilets and areas to relax as well as a barbecue outside
Bar- to use the bar you need one sim to tend and another sim can then order a cocktail for S2500, this cocktail will make them inspired
Do you have to buy all the areas at the Snow Park?
No, they are all unlocked apart from the Ski Lift which is still free but unlocks when you complete the Figure Skating hobby
You need the Snow Park to complete a goal in the Seniors Quest so make sure you have it built before then!