This is my first post! This is very simple. Do you have OS X? if so simply open the picture in preview. Simply double clicking the picture should do this. Click File...then click on export... At the bottom you will see a box that says format, click the drop-down box and choose the format you wish to use. Simply click save and that's it. You shouldn't hate mac, it's really a great OS. Let me know if that didn't work.