If you do not have an operating system on the disk I do not know how you are seeing a pic of the beach, but in any case, to change the boot order in bios so that you can put a new operating system on the disk watch the bottom of the screen when the computer starts for it to say something like, "press del to enter setup". Instead of del it might say, F2 or some other key. Push that key and go into the bios, look for something that says something like "boot order". Once there you can use the arrow keys on your keyboard to change the boot order, it should be set to boot first from CD Drive, then C drive. The CD Drive might be referred as "Optical Drive". Save the changes and then let it restart the computer, make sure the XP disk is in the drive.
Post number two at the following link gives really good and easy step by step instructions on reinstalling Windowshttp://www.bleepingcomputer.com/forums/t/231511/reinstalling-windows/
Post back and let us know how it goes and if you have any problems along the way, post back with those too.