Hay man not sure how old u are, But if ur under 22 around abouts stay clear of PH's and AAS until you get some size on you naturally 1st... any younger than that anyway and your test lvls will be through the roof so they will only do u more harm then good.
Diet is the biggest factor and you can put on massive amount of size/weight by eating clean enough calories carbs. proteins ect ect. To put on that size though also heavily relies on your training experience if your fairly new to training (begginner) youll grow like a weed on any program putting on 20+ pounds in a few months. (Just look at mark rippetoes starting strength claims) BUT AGAIN, that falls back to your diet. (make sure diet is in check, post what your eating and when your eating on the forums to get feedback. coz sometimes u think your taking in 1000's of calories until you put it down on paper and find u aint eating anywhere close to what you should be)
Natural Testboosters arnt to bad there always improving, novedex xt, diesel test, T-911 just to name a few theres heaps out there just gotta research and do ur own homework on that 1...
for a 1st timer i think just get the trifecta stack by LG Sciences, if that goes well after a fair while try another substance a lil stronger and so on, but imho stay away from orals if possible, learn to pin if u must do AAS... There not healthy by all means, and ppl that dont respect them give them bad names. but if the proper homework/study/preparation is done and has been gone over 1000 times to make sure all is in check, so if the worst comes to the worst your prepared!!