HCG will come in powder form and must be mixed with bacteriostatic water and stored in the fridge. It can last about 60 days when stored properly after being mixed. You can inject either IM (intramuscular) or subQ (subcutaneous). Dosages vary wildly and many guys run very high dosages. I would recommend 250-500iu's 2-3 times per week if using on cycle.
There are many ways to use hcg, you can use it on cycle the whole way through, or you can use it as a kickstart to pct. If you use to kickstart pct, I recommend using 500IUs per day for 10 days, while the anabolic steroid esters are clearing the body. Once hcg use is stopped, begin your pct as you normally would and recovery will be a breeze.