How do I make a picture that is 5.1 Mb smaller for Myspace ?

I edited this picture and its now 5.1 Mb . Can someone tell me how to make it smaller for Myspace ? I already have it on Facebook . I also have the Photoshop Cs4 program on my Mac and I saw the thing that says change photo size but it never works! the picture is also a JPEG .How do I make a picture that is 5.1 Mb smaller for Myspace ?
Try to use this picture resizing tool http://www.softorbits.com/batch_picture_ It works well!How do I make a picture that is 5.1 Mb smaller for Myspace ?
Open in Paint and save as a .BMP
http://www.shrinkpictures.com/