I have a good friend in you.
I have found/find a good friend in you.
What is the difference between #1 and #2?
First of all, you can't can "I have find." You are trying to use the Present Perfect tense, aren't you? So, "I have found a good friend in you" is grammatical, unlike "I have find... ."
Now the question is what's the difference between the present simple (I have) and the present perfect (I have found). Well, if you say "I have a friend," you are talking about possession: I have a mother, I have a job, I have a car, I have a friend.
If you say "I have found a friend," you are talking about an action which is completed by now: I have bought a car (so, I have a car), I have watched the film (so, I know what it is about), I have found a good friend in you (so, I have a good friend in you).
All in all, sentence 2 is about the action which has led to the result, and sentence 1 is about the result.
Having read the comment below my answer, I'd like to add that if you say "I find a good friend in you," you mean a regular activity. It's like "I always/usually/regularly find a good friend in you."