The Mesh Edit tab contains several tools for, in general terms, adding geometry to your mesh to go on adding more detail.
Let me show you the most interesting and useful tools you will find here:
Slicing a mesh can be a good method of defining more interesting shapes. Let's take a look at how to use this tool.
The following screenshot shows the use of the Curve Slice tool. As you can see, you can make cuts with curvy shapes:
Viewing your mesh from a non-perspective view (better for this tool), start drawing a ...