Using carpet tacks to put down a small carpet
I'm currently finishing off my son's very small bedroom. The floor boards were bad and gappy, so have laid down hardboard over them. I have now put down the underlay (using carpet tacks around the edge). I have to now just put down the carpet (the carpet was so small (L-shaped bedroom) that it was not eligible to be fitted free of charge by the company that I bought it off of). Somebody suggested carpet tacks a while ago to me, which I have used for the underlay (used hardboard nails to put the hardboard down), however, the carpet is royal blue and I've tried pushing a black tack through the carpet sample and obviously the black head shows on the surface of the carpet. Am I supposed to hammer these tacks in so they go down right into the fibre of the carpet (felt-backed and hard) and then try to move some fibres over the top of the tack head to conceal it, or do you just nail them in so that the carpet tack heads are still showing? Any advice would be appreciated. Thank you.