"even" can be an adjective, for example:
"My teeth are even." - It means my teeth are straight and I don't need braces.
"even" can also be used as an adverb like this:
"I have been to many places. I've even been to China."
"I have even passed my math exams."
"I don't even know what to say about you."
"Even the best of us make mistakes."
"Even you can do something about it."
You basically use "even" to make your sentence sound stronger, that there is something special about the verb you will use. "I have EVEN been to China." sounds like China is so far away but I EVEN got to go there during my trip. If you only say "I have been to China" then it is just a neutral statement without implying that it is something special.