I recevied a free

Imac, I have vary limited knolage of them and need to remove the passwords. I am going to clean the computer and give it to a person who can not afford to buy a computer. It was from a company that went out of business and auctioned off equipment. It is blue with a frount loading cdrom, by the seireal numeber and tages it is 333mhz, 512 mem and mabie a 20 gig drive.
What else do I need to tell you about it?