Try changing the order of announcements that are generated on the same day by rewordin g the announcements. You may copy and paste text or use existing HTML files. In fact, the CMS allows you to seamlessly upload your files to the server without having to go through the confusing FTP process. Typically gifs are used for line art and jpegs are used for photographs. Both use compression schemes that make the files sizes smaller and therefore more convenient for Web use.
Most image editing software can convert other image types to gif or jpg.