Moving a cursor around a sphere

[Brainer]

System: Windows XP SP 2 (Pentium D 805, 2 GB RAM, GeForce 7600 GS)
Compiler/IDE: Delphi 2007 for Win32
Libraries/API: None
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Hello there!

Let's assume I've got something like this:



In the picture you can see a plane, a sphere and a reticle placed on the sphere. I'd like to know how to move the reticle around the sphere? Also, when I move the reticle, the plane should direct at the reticle. Additionaly, the reticle should have something like a max and min angle (like 90 degress up and 90 degress down).

Do you know what I mean and could give me any useful hints/code snippets, please?

Thanks in advance!