Auctions work with a starting price (The minimum sum), a minimum raise sum and an optional buyout. These suggest how much you want for the head texture. If a head texture has a starting price at 500 TC, a minimum raise of 100TC and a buyout of 1000TC, the first person must bid 500TC or more. The next person must bid 600 or more. If someone is very interested, they can offer the buyout price of 1000TC. If they do, the auction is closed and this person gets the head. The pricing is entirely up to you. Watch some other auctions to see prices, and compare the quality to your own heads.

Next time, be careful where you post. This isn't Support material.