Your trying to focus the scope you currently have on it? ... turn the lock ring off first. If not, you will tear your hands off before you tighten against that ring. The aim at the sky or a plain wall and turn the eye piece counter clockwise. Ajust the focus until the sight picture is nice and clear. When you are satisfied with the focus, then retighten the lock ring.

The very small back ring on the end of some scopes is the fast eye focus. To use that, look at an object in the distances for about ten seconds, then quickly look through the scope and adjust the fast eye focus until it is clear.