i do not have an instruction book?

Rose, you don't say the make or model of your oven?

No matter...

On my oven there's a bank of buttons under the digital clock display - to set it I turn the power off and on again and the digits flash on and off. I depress and hold buttons 2 & 3 from the left and at the same time use the Plus and Minus buttons to set the time - yours may well be similar.

Good luck...

Peccavi
September 2009