we won’t really know him, unless you let us inside.
You show the inner world of your character by telling the reader his thoughts, emotions, attitudes, fears, longings, neuroses, drives and compulsions. There are two kinds of thought your character has: (1) thoughts about events that have occurred and (2) peripheral thoughts.
Writing dialogue can be a little bit scary. It’s quite normal to be nervous about it, or even a little fearful. Every writer has his own style and voice (eventually) and nothing shows that more than writing dialogue. It is through speaking that we get to know other people best. It shows us what kind of person they are and it shows them what kind of person we are. The tricky bit is, as writers, we are all kinds of different people, depending on which character we are voicing.