47-55.1 Sheet Metal Console

[Driver_WT]

Hello everyone, we are making a sheet metal console for my 53 Chevy truck. The main part is being from two pieces of a sheet metal trailer fender. The trailer fender has a curved edge on one side and a flat edge on the other side, so we split the two trailer fenders down the middle and used the two pieces with curved edges to make the main part of the console. When the two pieces were welded together, it created a bit of dip in the middle of the console and I would like it to be flat. I have a hammer and dolly but don't know how to use it to take out the dip in the center. Can anyone enlighten me on the basics of using a hammer and dolly to work out a dip in sheet metal?

Thanks.

Wade