Hi Hary,
Welcome aboard!
I guess that what you mean is setting up the intonation of your bass.
There are some clear step by step instructions at the following page:
http://www.fender.com//customshop/basssetup.html
They are written for fender basses, but as the fenders still are
THE standard basses the instructions are going to help you with any bass. You may have to use other tools, depending on your bass, but the basic principle is all the same.
Hope this helps!