Just an addition to what Jim has already said:

Please take the time to do your research first! Don't just go to a "backpacking store" and ask for help. Most of the clerks, even at places like REI, have little outdoor experience. You will end up with a maxed out credit card, unnecessary gear and often heavy (but not better) gear that you can hardly lift.

Borrow or rent as much gear as you can for your first few trips. Try to go with someone experienced or with an organized group. Groups are great because you can share a lot of gear (tents, cooking gear) and you can see lots of gear firsthand.

I don't put much stock in the "gear reviews" on retailers' websites (I know that several unfavorable reviews I've sent to REI were never published). There are a number of more impartial review sites, especially backpackgeartest.org. Mark Verber's encyclopedic website has a rundown of the various types of gear and the materials used in them. I don't necessarily agree with many of his recommendations; the key feature is that you will learn about many types of gear and can get a good idea of what is available and what will suit you. The articles on the home page of this site are a great introduction to gear selection.

It's fine to study gear lists, but be sure the author of the list is using the gear in the same environment you will be using. What works in southern California will not necessarily be adequate in northern Washington, nor in the Rockies. Note that the gear lists on the home page of this site are for the Cascade Range--a bit harsher (and wetter) than the Sierra but milder than the Rockies. The environment where you backpack may be quite different.

In addition to gear, there are skills that need to be learned: How to keep yourself and your critical gear dry. How to regulate your body temperature. Navigation. How to research advance information that determines what gear you need to take. How to use your gear--right down to how to pitch that shelter quickly and easily (best practiced in the back yard or while car camping), and how to set up and pack up your camp in pouring rain. That's why we recommend really short trips or back yard camping to start out, so that if everything goes wrong (happens even to the best of us occasionally) you can bail out to your car or your nice warm bedroom.

As Jim says, Learn to use it and enjoy getting out in the wilderness! That's what it's all about!