Surface fill is a good one to know. From your earlier post I assume you are trying to create a little dip in the seat for the guys butt? You can use s plit line to specify a region to get dipped, delete the face (choose delete, not delete and pathc or delete and fill), create a sketch for where you want the dip to go, then use a surface fill, tangent boundary, and select the sketch as a control curve. If that doesn't get what you want, you can then revert to a surface loft. Then knit everything back up into an enclosed volume and convert back to a solid.
Some folks use dome and deform too, but I prefer to have more control over what I make.
If, on the off-chance you are trying to model a texture - umm, don't.