Welcome to the PF. You must post your thoughts and the relevant equations, before we can offer tutorial assistance. There are basic equations for what you are asking, and they should be listed in your textbook. If you have no textbook, you can use wikipedia.org to look for information like this as you learn.
I'm having a similar trouble. I know that E= deltaV / distance but in my book there is a problem where the the point of question (0V) is a distance 1cm from the next equipotential line (200V). The delta V is 200V. BUT in this other problem there are ovular circles around 0V and the equipotentials are 25V, 50V, 75V, and 100V. There is a point on the 50V line and the book says the delta V is 75V... What gives? Why is the delta V not 50V?