Hi, Michael, if you're using Windows for your operation system, you probably have Microsoft's Paint application installed, which is relatively simple to use and can be used to edit picture files (like jpegs). You could probably find it in the menu under Start>All Programs>Accessories>Paint.
Also, as Randy noted, the hosting site Photobucket has editing functionality available, so if you're using Photobucket to store your pictures and have them available to link into other websites, you could try their editor and see if you like it. Both of those choices require no downloads.
I'm pretty sure that most hosting sites have editor functions available (eg, Fotki), so if you use some host other than Photobucket, you might want to see what they have available.
I use MS Paint and the editor at Photobucket, and find them relatively easy to use.
Prost!
Brad