You may want to look at some Trigonometry. The COS(Angle) and SIN(Angle) commands are used for the cosine and sine Trigonometry functions.
Here's an example. It doesn't use sprites though. I just made it for ya (it helped me too)
rem *****************************************
rem CIRCLE ROUND BOX EXAMPLE SING COS and SIN
rem *****************************************
rem Set The Radius of our circle around the box.
Radius=50
rem Set The Target X position.
TX=303
rem Set The Target Y position
TY=303
rem Set The Speed
Speed=1
rem Begin Loop
do
rem Clear screen so the circle won't leace a trail.
cls
rem Print the controls.
set cursor 0,0
print "PRESS THE UP ARROW KEY TO INCREASE THE RADIUS."
print "PRESS THE DOWN ARROW KEY TO DECREASE THE RADIUS."
print " "
print "RADIUS: ",Radius
rem Control the Radius.
Radius=Radius+UPKEY()-DOWNKEY()
rem Create a box.
box 300,300,306,306
rem Go to our circleround label.
GOSUB CircleRound
loop
rem The Label
CircleRound:
rem Loop the angle.
ANG=wrapvalue(ANG+Speed)
rem Set the target X position to the Cosine of our angle. Then, add our target to it
rem in order to make it go around the right point. We also need to multiple the cosine by the radius of our special circle.
x=TX+Radius*COS(ANG)
rem Same on the Y, but use SIN this time. If you swap the two, the circle will go in the opposite direction.
y=TY+Radius*SIN(ANG)
rem Finally, place our circle.
circle x,y,2
rem Go back.
return
