After looking at the photo again, I'm assuming you are trying to sell. To the right of the green "BUY" box, you should click the "SELL" box. This will change from a limit buy to a limit sell order.
If you are trying to BUY more btc at your rate of 8050 then you will need to transfer USD into GDAX.
I was trying to buy so you are absolutely right, I need money in my USD. Thank you so much