On the left under clock will see round button with letters I believe says scu or something like that. Press and hold that button down with other hand look for up and down arrows but not the one on extreme right. Push up or down to set clock. When it reads correct take hands off arrows and the little round SCU button. Your set. I might be wrong on one of the initials but you will see it and no other round button looks like it

Go to ebay spend a couple bucks to buy an owner's manual for the vehicle, put it in the glove box.
Open the glove box, pull out the owner's manual and look in the index under radio and/or clock, note page numbers.
Turn to that page and select the type of radio/clock you have and follow the instructions to set the clock.
Drink a small bottle of wine, smoke a joint and ponder why you could not figure this out yourself.