The internet is full of many, many tutorial sites. If you open up your google search bar and type in Webdesign Tutorials, I'm sure you'll be bombarded by tons of sites (some quality and some not, probably) that can assist you in learning the basics.
http://www.photoshopcafe.com <-- thats where i started, they teach you the basics of photoshop and the guys a really good designer so it should be fun for you.
also try to look at a lot of portfolio's from designers here at tf and such. Try to 'recreate' designs you like, zoom in on certain areas and try to figure out how certain effects are achieved. That's how I learned a lot.