HomeBrewTalk Forums is a really good place to start. Their search function is Google based so it's pretty user friendly.
Brew In A Bag (BIAB) is a way to do all grain batches without having to use a mash tun. The difference between using a mash tun and BIAB is that a mash tun has a filter and spigot at the bottom of the container to drain the wort from the grains while BIAB is just what it sounds like, you have the grains in a mesh bag that you just pull out to separate the wort.
You'll probably see a lot about sparging, most people with BIAB do not sparge and just squeeze the bag.
Best bet is to get a ingredient kit from somewhere like Brooklyn Brew Shop. They have a good selection of 1 gallon batches.
My biggest piece of advice when starting home brewing is to not worry about the small things as much as you think you should. Practice basic technique until you get the hang of it.
Sanitization and temperature control is key.
