Sonic The Hedgehog,
I have attached to this post source code which solves your problem. It needs no media, so just copy and paste and run it. The code is fairly simple and is printed with a comment for each section within it.
By the way, in the code you wrote above...
cls
sync on
sync rate 30
circle 300,300,20
if mousex()<100 and mousey()<100
cls
...is definately set for erros. You are missing the
endif part of the
if statement, which is checking for mouse coordinates. Also, you have turned manual
sync on, but have not included the
sync command to manualy refresh the screen.
+NanoBrain+