"Am I a witch? How can I become one?"
I see that a lot of people ask this question, so I'm going to answer it with my opinion(s). I believe everyone has the ability to work with magick and cast spells and such. A lot of people who are new to the craft or misinformed think you have to do something (like in the movies) to become a witch. There is no transformation on the outside, but on the inside there may be.
You don't. However, practicing the basics and working on yourself would be like 'becoming a witch'. You are preparing yourself to use magick, opening yourself up to it after being told for several years it wasn't real in some cases. You are re-routing your beliefs, starting a new limb to the tree. I would definitely count that as 'becoming a witch'. Other than that, however, there is no magickal way to become a witch, since we basically all are witches. It's just whether or not we choose to alter our beliefs and start walking our path, researching, opening up to the things we knew nothing about before. We all started somewhere, somehow.
So to those of you wanting to become a witch, Start by researching, reading, looking inside yourself for answers. Work on the basics. Start a new path. Find your interests, incorporate them into your path. Have fun.