I'm assuming you're new to the game and need some tips getting around. You'll find games to play in Adventureland: Pirates and Jungle Cruise... Fantasyland: Fireworks...and Frontierland: Haunted Mansion. There's a button to push at each game that explains how to play. Doing this, you can have fun and earn credits to buy stuff. There are also games to play in the Tomorrowland Arcade. You get there from the Tomorrowland Hub by going to the thing that looks like a VMK Kiosk. You can win codes for stuff.
You'll find stuff to buy in the different shops. There's one in each land and they each sell different stuff.
You can also win stuff when the hosts open their special rooms. You'll see those listed on the VMK homepage.
Every day you can go to the Music Game and play a song to make credits. You also get credits when you make a new song (and make a new song/remix a song each day.)
Do the following every day:
Go to Shrunken Neds and click on him for 20 credits.
Go to Pirates treehouse and click on Capt Blackheart for 20 credits
Go to the Haunted Mansion and enter the crypt at the left. You'll be inside the stretching room. Wait for the ghost Phineas to appear then click on him. 20 credits! Exit to the right to the Banquet Room and wait for ghost Ezra. Click on him for another 20. Exit to the right to the attic and wait for Gus. Another 20.
Go to Fantasyland and find the dragon in the dungeon. Clicky clicky! 20 credits. The find the Yeti in the Matterhorn for another 20.
Having fun yet?
You can click on the "chair" button at the bottom of the screen to see how many credits you have and look at the stuff you've bought. Put the stuff in your room and invite your friends!
There's even more... but this will get you started.