Take a look at this for some ideas: http://www.curso-ingles.com/gramatica-inglesa/even.php

There are a couple of different definitions for "even," but I think you are probably asking about the adverb use. We use this for emphasis. It's a little challenging for me to explain more than that. Some examples: I don't think he even wants to go with us. (emphasize his lack of desire) Even my little sister can understand the rules to this game. (emphasizes the simplicity of the rules) She has even fewer friends than I thought! (emphasizes how few friends she has)