Will it be something like this? I added a cylinder with vertices 8, then I went into edit mode to delete half the faces and added the subsurf modifier and one loop cut:
I have some more questions. Do I need to set the cylinder vertices to 8 since I will use the subsurf modifier? By half a cylinder do you mean going to edit mode and deleting half of it? Lastly when should I add the subsurf modifier? Thanks!