Can't save pictures in jpeg from photoshop

Hello,




Hello good day. i have a problem. i am using adobe photoshop cs5.1. everything work properly but as soon as i am to save it . it won;t save in jpeg. i tried but i have to close it and it would say if i want to save it in jpeg . but it doesn't it save as that. i would want to know how to get the box to open with save as with options at the bottom so i can choose what i want it to save as. please and thanks.