There have been countless threads on this same topic. Check out this thread:
It all comes down to what you want to do with linux and choice. When you find one you might be interested in, download it and set it up on your computer. When you have a question, post a question here. When you become comfortable with linux, then you might want to try out a different disto(s). One helpfull hint, learn to do a search on this forum. Your question(s) might have already been answered, and it will get you an answer quicker.
Good luck, and welcome.
Also check these two sites: