Making Nemo Move...

So, I am creating a fish tank in which fish move depending on their speed and hunger. But the latter doesn't matter for now.

Basically I have my tank, with buttons on the east side of a border layout that allows fish (currently Nemo) to be added to the tank. The fish appear at random pixels in the tank image, which is on the west.

Currently, I am having alot of trouble getting the fish to move. their X,Y coordinates are stored in the class Fish along with their speed etc.. I have been told about threads but I am unsure how to use them properly and where they should be placed, as in what class..

If anyone could shed some light and guidance, or even help me on MSN to some extent I would be eternally greatful.

Thankyou guys,
Danny

PS. If requested I can post code (or send code) but it's too long to include in the post..