@alliereyaz. Mate, taking supplements is another thing and steroids another. Generally our gym owners here sell steroids in the name of supplements as they give fast and good results so the customers are satisfied. Taking supplements is not an issue while taking steroids is because then one gets addicted to being in a shape which can't be achieved otherwise. If you don't want to get into competition and stuff, why would you take steroids. Remember, there is not a single pro athlete who doesn't take steroids in some form be them your favourite cricketers too 
i recently join gym (about one month ago) im 6.3. my instructor he was junior mr. karachi he told me that i should take supplements of proteins by taking this my bones got stronger and work inside from my body. he also said that if any thing goes wrong just came to me. i assure u nothing gonna happen.thn i decided to take supplements, but ive to ask u and here that i want to be a builder should i go for it and what other things should i ask to my instructor?