take pw23 advice seriously. I wasted a year working out incorrectly. It's the small things that count, eating right, form while training, how many sets/reps, etc. You probably know very little about that stuff now and there is always something to learn regardless.
If you don't want to join a gym, i suggest you research everything you can about working out for what you want your body to look like, books, forums, online articles are very helpful. Before you even start you should do this, a week or 2 of researching will save you MANY MANY hours in the gym.
Once your done researching make a routine, what your gona be eating everyday, cardio, weights. Than save up for the machine, weights you need. Than start pumping and you will be ripped a lot faster than doing it the stupid random way, like i did. Your lucky, your on this forum, I didn't even know about these things before I started working out loll. They are very helpful most the guys know what their talking about.
Also, don't target a set of muscle, you MUST work the whole body. It's MUCH healthier and you will grow a LOT faster and more efficiently