You're not too far from what you want to do.
One of your first problems is that you are trying to put a graphics command onto the default screen, which is text only. Take a look at the help for the SCREEN statement and SCREEN MODES. Use SCREEN 12, which is 640 x 480 VGA screen.
The program will now work, but I don't think it's working how you want it to. It IS drawing 15 circles, but all of one colour (1 = blue) and on top of eachother at 10,85
The point of FOR loops is that you want to use the loop a certain number of times. Almost everytime you use these, but not always, something is going to change. It may be counter, a calculation or whatever. In this case you want the positioning and colour to change.
What you need to do is introduce a variable that will change as it goes through the loop. The variable will control both the positioning of the circles and the colour.
You've already got such a variable. It's n. This is what controls the number of loops. Now you've got to use it to control the positioning of the circles and their colour. Try this :-
CIRCLE (10 + 20 * n, 85), 7, n
Every time the loop goes around the centre of the circle changes. The first time it is at 30,85 the second time it is at 50,85, the third time it is at 70,85 and so on.
Replace the 1 at the end of the line as this is the colour that is used to draw the circle. Now each time the loop is stepped through the colour the circle is drawn it changes.
Now for the PAINT command. The centre of the fill needs to be inside the circumfrence of circle, otherwise the whole screen will fill with that colour. The centre of the circle is the mosy obvious to use. So use the same positioning as the CIRCLE command.
The fill colour has to be the same as the circle so change the 1 at the end of that line to n as well.
You should now have enough information to rewrite the code so that it works.
Ray