Here's one way...
To get your pics less than 100kb, you'll need to resize them using a photo editing application such as Microsoft Photo Editor, Photoshop, or the like. Your computer probably came with at least one already installed. Every program is a little different, but most have a toolbar on top that says "Image" (to the right of "File", "Edit", etc.). Under the "Image" toolbar you should find some sort of function that says "Resize". After clicking on this a menu should come up where you can then choose how much you want to shrink (or enlarge) your picture. The smaller you go, the fewer kb your picture will be. After shrinking, just save it under a new name (so as to preserve the original). Hope this helps!
-Stew