The Pro Tools setup will normally ask if you would like to install the plugins. However, if you did not elect to install them, they can be installed later. Here's how:

Go to your Pro Tools CD-rom, go into Digidesign Plug-In Demos folder, and either run Setup, go into the D-Verb folder, or run D-Verb Setup (depending on which version of Pro Tools CD-Rom you have). Select D-Verb and continue through the installation. When you go into Pro Tools, it will say there are 10 days left in the evaluation period. Simply click Register Now, and insert your D-Verb floppy disk. This will move a file from the floppy disk to your hard drive. D-verb will be available just as any other plugins.

If, in the future, you choose to format your hard drive, you'll want to run a file on the floppy which will copy the file back from your hard drive (before you format it and therefore lose this file) and allow re-use of the disk.