Image Display Problem

I’m very new to wordpress, and recently I’ve tried to put some pictures into my posts. I’ve uploaded the images, and used the tags wordpress gives me to try to put them into my posts, but when I view the posts, all I see is the little red “x” internet explorer gives you when it can’t find/load/whatever an image. Is this a compatability issue with internet explorer because WP is optimized for firefox, or am I doing something else wrong? Any ideas?