How do i get full screen on my mail, there is always an ad at the right of the screen?

there is an ad on the right of the screen. it takes up about 2 1/2 to 3 inches. i can't see the entire e-mail without slidding the bar at the bottom so I can see the right side of the e-mail.also i can't see a whole picture that has been sent I have the use the slider on the right going up & down. I only see 2/3 of the picture.