Well, at leat you asked, and in the correct section.
No it does not cost anything to set up a thread in BST (except possibly your account if you dont read the rules)
A review copy is just what it sounds like, you offer to give someone (preferably a mod or someone whos been here a while with high posts and or iTrader) a free copy of your service, and in return they will post their review in your thread.
That way if you are selling total shit, they will mention it, and no body will buy from you, but if you do a good job, you will make sales.
just post clearly on what your service. give an accurate description of the service and be truthful about the time it will take to complete. Many providers deliver more than they advertise to keep customers happy and coming back for more whatever you got.
offer as many review copies as you can afford to as it will just give you more credibility if your service is good.
dont bump your thread or go into others and offer service or do any shady shit and you will have a good customer base if you are offering a quality service.
hey how can I edit one of my posts? I don't see the option anywhere
You can only edit posts up to 10 minutes after you originally posted it. If it's a thread in BST, you can ask a mod to edit it for you. Otherwise, you're stuck with what you wrote initially.