I would start at your local library. Look for books on hiking and camping or backpacking. If you have one nearby, a used bookshop may have some books as well. The Boy Scout manual would be a good start. Also, there are dozens of good websites with gear reviews, hiking tips and instruction, lessons on weather and navigation, first aid guides to local areas all over the country, you name it.

YouTube has hundreds, or more likely, thousands of videos of the same--gear tests, trips people have taken, instructional videos on any subject you can think of. Some are put up by companies who want you to see how their products work, but most are by campers and hikers who want to share with others. Lots of DIY projects, too. You can learn how to make an alcohol stove, make a shelter, start a fire, cook, how to choose campsite, use a compass, pretty much everything you'll need to know.

For clothes and gear, consider your local second hand shops. You'd be surprised what you might find in them. Not all will have any camping gear, but you may find nice shirts, pants and jackets very cheap. Look on Craigslist for things like sleeping bags. Many times people buy gear then decide camping isn't for them or they buy new stuff and sell what they have. EBay is okay if you know what you want, otherwise, better to see what you are getting in person. I got my big red parka on eBay but I spent a lot of time looking for a big parka before finding it.