Here's a decent one for the basics:
http://www.escape.ca/~rrrobins/Assembly/

This page looks like it's got some useful stuff, including a link to an ASM compiler (MASM):
http://webster.cs.ucr.edu/Page_asm/0_Page_asm.html

And this one looks like a great general purpose resource site (some of it looks pretty advanced, though):
http://www.azillionmonkeys.com/qed/asm.html

These are a couple pages that might be decent to help you out. I'm not sure what kind of background you've got or anything.

I think I'm lost.