I want to give away my D620 emachines laptop, but want to reset if first so all my personal information is erased. How do I do this?

In order to completely reset all personal information, the only failsafe way is to wipe the hard drive (and even this is not failsafe).
Look at this program. This program will allow you to make a bootable disk (eg USB). After you create the disk, reboot your computer and press the Boot Order key (on a Dell D620, its F12). Select USB. The Kill Disk program will load, allowing you to completely wipe your hard drive (eg. by overwriting everything with 0's). This will probably take a while, depending on the size of your hard drive.