Three questions (sessions and frames)

I am currently working on a web-portal and there are some things I have had problems with...

1)How does sessions work in asp.net? I have a page where I validate the user against a user db, what should I do then, when I redirecting him to the main page? Where do I create session objects? What should there be in those session objects? I am only focused on using the timeout feature... how do I do that?

What things SHOULD I use sessions for? Can you give me some examples on practical things... This is NOT a webshop I'm building :)


2)How can I use frames on aspx pages? On the intro page I need two frames, one with a color and one with an aspx page... is it possible?