http://www.learnmicrosoftbi.com is an excellent site to learn SSAS.
Use the following link to signup.
http://www.learnmicrosoftbi.com/Home/tabid/37/ctl/Register/Default.aspx?returnurl=%2fVideos%2ftabid%2f75%2fDefault.aspx
After you get your password use the following link to watch the videos in SSAS.
http://www.learnmicrosoftbi.com/Videos/tabid/75/Default.aspx
Happy Learning