my suggestion is to get photoshop if you don't already have it and learn to use it. there's probably thousands of tutorials on line but you can start here:
tut's
also, ulead's photoimpact has some great button and other graphic wizards to make some of the simple graphics easily. you can d/l the demo or get a copy at your fav hangout.
for design and tips here's a cuple of sites that might help:
webmonkey
htmlgoodies
but i would suggest finding some site online that you like the layout of and just emulate them, changing color schemes and graphics to suit you desires. you might consider using dreamweaver for site design if you're not writing code yourself.
with time and experience, you'll be creating whatever you want.