Subbing since I know very little about this too, but here's my two cents...
I've read a lot on this site: http://babyledweaning.blogware.com/
I'm not entirely sure what the general theory behind it is, but I know for me, it's mostly about letting DD be in control (somewhat) of eating solids just like she's been in control of eating breastmilk. It's also, to be honest, about doing what's easiest for me because I'm a lazy mom!
I also really like the idea of giving babies "real" food instead of "baby food." For me, giving DD mush didn't seem to make sense in my head; if they have a tongue-thrust that prevents them from swallowing anything other than liquid, then doesn't that mean that they aren't ready for anything other than breastmilk? And if they no longer have the tongue-thrust and can eat actual solids, then doesn't that mean they're ready for, well, actual solid chunks? So that's how I started baby-led weaning.
DD is now seven months. Her first food was banana, which I mashed up a bit and gave to her on my hand (I held it out and let her pick it up and eat it) when she was six months and one week. She gagged on it and didn't seem happy at all, even though she did eat a little, so I waited a week before trying again. We tried avocado a week later (since it's naturally kind of mushy), and again, I let her pick it up with her fingers and play with it. Again, she didn't eat much, but she liked it better. Now I've let her try lots of things...steamed broccoli, honeydew, raw apple, rice, & green beans. She likes playing with food but never eats much; she's much more interested in nursing still.
I'm waiting to try any likely allergens (dairy, soy, egg, corn, wheat...) until she's at least a year old since DH had a lot of allergies as a child.
I really love this a lot more than spoon feeding! I feel good knowing that DD is choosing how much to eat, and it's so much more fun to watch her feed herself than to try to get her to take a spoon.