You can enable/disable breakpoints by clicking on the left margin of the code in Visual Studio (where the red circle is)
A red circle means there is a breakpoint, and the execution will pause when it gets there (make sure your configuration is Debug Editor). So place your breakpoint on the line where GetDisplayName gets called, then you can use F10 to advance one line, F11 to step inside the function at the line you are at, Shift+F11 to step out, F5 to continue executing normally.
If it doesn’t work that way, check your Visual Studio shortcuts to see what keys correspond to what debugger actions.