I use photoshop 6.0, so it may be a little different, but should be roughly the same.
Click for grid tutorial
... just stop when you need to, unless you want to keep going ^^;
There's a brush in Adobe you can use, it's a preset. Click the brushes button, then you'll see your circle and the little arrow. Click the arrow and a menu'll come down. Select Assorted Brushes (or something like that) and select append if something pops up at you.
You can then "paint" the little guys on. And you can use the transform tool (select the starishthing with the marquee and click ctrl-t) to make it bigger or smaller (shift if you want it proportionate).
And yah... hope that helps.