That too is a broad question, just like your last one. Please show us that you're not "harvesting" answers and actually show us that you're learning something. We need to know that you've tried doing it already and what you've tried. You should have a concept of what to try already, as it is fairly simple:
Moving diagonally involves incrementing/decrementing the X value and the Y value of an object. The only other thing you need to do is have it in a loop so it keeps moving, and make sure to draw and erase the object. This would be an example of text moving diagonally:
0->A
0->B //instead of X and Y, I use A and B, since the OS resets user variable Y when dealing with the graph screen.
Repeat A=50 //about the bottom of the screen
Text(A,B,"TIBD"
Text(-1,A,B," " //just add enough spaces to erase whatever you're drawing
A+1->A
B+1->B //you can change the increment value so that you get a different slope
End