Question about membership levels

I don't understand how to make the whole website free and to use the plugin to protect only some areas.

In my case i need to do this:

FULL WEBSITE - fully visible to all people also not registered

RESTRICETD PAGE A -> visible only to user of level A
RESTRICETD PAGE B -> visible only to user of level B
RESTRICETD PAGE C -> visible only to user of level C

Btw i'm also unable to see the WIZARD, misteriously there is not in mine installation... how can i launch this wizard ?

Please help me !

Thanks