Yes, you can use graphics from sources other than iScrapKits with iScrapbook. For example, you can use images you already have on your computer or images you legally downloaded from the Internet. iScrapbook works with most popular graphic file formats such as jpeg, tif, png, pdf, gif, etc.
There are three easy ways use graphics stored on your computer.
1) You can simply drag the graphic file from the Finder to the Design Canvas (your scrapbook page). This is described in the section, "To add a graphic from the Finder to the Design Canvas" on page 40 of the user's guide.
2) You can add the graphic to the Favorites Bin where you can easily and conveniently use it whenever you want. You can organize your graphics into collections in the Favorites Bin to make it easier to find and use graphics. For more information on the Favorites Bin, see page 45 of the user's guide.
3) You can choose Insert > Choose Image and then choose the image you want to put on the Design Canvas.