Mouse problems on Windows XP guest on Windows 8.1 host

[Wally64]

I am running Windows XP on Windows 8.1, and I confess I have the most basic of questions. I tried to look for the answer on the forum. Very simply, I am trying to determine the way in which one makes the mouse active on the guest OS (in this case, Windows XP). When I move the cursor to the edge of the inner screen with XP, the cursor disappears, and cannot get it to appear.