Ripping plywood - table saw

So I've been building items from Ana's site since this spring.  I've
managed a few different projects, but I've been ripping plywood
lengthwise with a circular saw a a jig I made following instructions
someone posted from the woodworking.about.com website.  BUT

I got a table saw the other day and for the life of me I can't figure
out how to do this or to cross cut the strips afterwards.  I get stuck
every time trying to figure out how to manage to make sure that I cut
square when the widths/lengths of the boards are bigger than the "deck"
of the table saw and I don't have anything to but it up against to keep
the wood going into to the blade straight.

Can anyone out there help/tell me how they do it?

Thanks

Carrie