Hi welcome to the forums..!~:D
You want to make a game similar to Myst? I myself have never played Myst, so I can't help you there...and I'm not sure if you can..I gather it depends on what you want to do..
That being said, are u familiar with Adventure Maker? with variables...?
Do u have the Full Version of AM or Free version...
If you have the Free version and aren't familiar with AM..try playing the example games that come with AM...to get a better feel for it..as well as other games made with AM on the games page as well..!~
http://www.adventuremaker.com/phpBB2/viewforum.php?f=5
Not all are available...and
Here are some more in the forums..
http://www.adventuremaker.com/phpBB2/viewforum.php?f=5
Someone else may come along to better help you as well...~