Summarize this article in one sentence.
Make sure that the disk is inserted before you go looking for it on your computer. Ensure that the disk is inserted rightside-up. Make sure that the disk lock is not engaged before inserting the disk. When formatting a disk, all the information contained on it will be erased, so make sure you've backed up anything you need to save. You can access this by clicking the Go menu, selecting Utilities, and then selecting Disk Utility. It will be listed in the left frame of the Disk Utilities window. This is located in the right frame of the Disk Utilities window. In the Volume Format drop down menu, select "Mac OS Standard" if you only plan on using the disk with other Macs. If you want to use it with multiple operating systems, select "FAT". You can label the disk by typing a label in the "Name" field. Click Erase... to begin the formatting process. You monitor the progress by looking at the bar in the Disk Utility window.

Summary:
Insert the disk. Open the Disk Utility program. Select the floppy disk. Click the "Erase" tab. Select the format. Start the format.