To adjust the angle of the eMac, eMac (ATI Graphics) or eMac (USB 2.0) computer, you can use the eMac Tilt & Swivel Stand, available separately at http://www.apple.com/store/.
Follow the instructions that came with the Tilt & Swivel Stand to attach it to your computer. Then hold the sides of the computer with both hands and turn it side-to-side or move it up and down to adjust the angle.
That Apple Store link is dead now, but here’s how Apple described the Tilt & Swivel Stand on the eMac’s product webpage:
Apple designed this Tilt and Swivel stand (2) as an optional accessory. Using it, you can tilt eMac from -5° to +15° up and down or swivel your system 360°.