I am currently in the Marine Corps so I can't take a class since my schedule is always full because of training purposes. I was wondering what sites are good for beginners and professionals.
First of all, thank you for your service.
Depending on where you're stationed, you may want to check for classes anyway. One of the things I wish I'd done more of when I was in the Army was take advantage of the local college classes and rec center resources.
These days there are a lot of online college resources- and getting credit for promotion boards and potential job skills is always a good investment. Don't discount it- because it could be worth the hassle, and some units will give you a little more slack for doing college study than not. Heck, talk to whoever your local education person is, they may come up with resources that we wouldn't- I know the Army had a whole correspondence course thing for several career fields, and the MOS 4641 probably has a raft of interesting training materials, so it's worth seeing if they're available via mail.
If you've got a Public Affairs office nearby, you may also want to see if they've got a friendly photographer, or if there's a chance to do it for your unit. When I was in Germany, (right down the street from the Schneider Optics factory dammit!) one of my friends was the "official" unit photographer (and half a dozen other things) for our command- even though he was officially a medic- you end up doing a lot of grip and grins, but it may give you access to a wide range of equipment you couldn't otherwise get to play with.