I second everything in this thread. Don't worry about prohormones or steroids until you put a few years of training under your belt. Also, before you you fool around with your endcrine system you need to learn more about it.
You're priorites should be this:
Diet
Routine
Consistency
Recovery
Supplementation
As far as supplementation goes, don't worry about all the magic elixirs on the market. Most of them are sugar water, caffeine and snake oil. All you need is a good multivitamin, joint support, fish oil, a tub of creatine monohydrate and a tub of good whey protein in your favorite flavor. Maybe throw some extra BCAA's and fiber supplementation in there, too. Fiber is good for intestinal motility. You might be lacking in fiber since you're gonna be eating so much protein. There's nothing that feels better than a colon purging stool. lol
When it comes to diet focus on eating whole protein, complex carbs and healthy fats. Instead of eating 3 big meals a day, eat 6-7 smaller meals. You want your body to stay in an anabolic state rather than dipping down into catabolism. Which happens when you get hungry. Also, try to eat 1-2gms. of protein per lb. of body weight daily. Try to get the majority of your calories from whole foods. Don't forget to eat fruits and veggies. They're chock full of vitamins, minerals and fiber.
There's no need for a big crazy routine when you just start out. Stick to a basic 5x5 program centered around flat bench, deadlifts and squats. Also, before trying to go heavy, get your form down. You won't be hitting the target muscles the way you should if you're shaking, wiggling and wobbling all over the place. Check out stronglifts.com for some good, basic info. Like I said, there's no need for a big, retarded workout focusing on 20 different isolations, that takes 2-3 hours to do when you are starting out. You may find a routine that suits your personality better, but 5x5 is a good starting point.
When it comes to recovery, you need to give a muscle group at least 24 hours to recover before you work it again. Hypertrophy comes from "micro-tears" in muscle fibers signalling your body to grow more muscle to handle the extra stress.
O.K., back to using gear and my take on it. There's nothing wrong using it after you have everything above in check, are above the age of 25, know about the side effects and how to minimize them.
Don't fall into the trap that steroids comes first and everything else I've said above comes second. Gear isn't a magic bullet and if you don't know what you are doing you run the risk of gynecomastia, staph infections from improper injection practices, damage your liver and endocrine system. Also, you ain't gonna grow for squat until you have the above locked in. Steroids are the last 5-10% if you do decide to use them.
So, in conclusion, lift heavy and consistent, eat an abundance of clean calories, give yourself recovery time and lift with proper form. Do that for a year and you'll notice your weights moving up quick and your body getting it's swole on.