my computer went to sleep after initial set up, and now requires a password to open how do I find the password?

Didn't you set a password during initial setup? Anyway: this might help: Change or reset the password of an OS X user account - Apple Support

when you go to apple logo > click on sleep the computer will go in sleep mode .😁

Secondly if you tap on desk top it will prompt to enter username password please enter .

An apple article is there to follow : OS X Yosemite: Require a password after waking your Mac

Did you purchase this machine new? I am asking because your profile shows that you are running Lion which would indicate that it may be a used machine if it is new to you.