Your cham has to get use to you first. When I first got my cham, he wouldn't even stay at the front of the cage when I came to look at him. Everyday I would stand and look at him half an hour, an hour at a time. He finally got comfortable with me being around. After he was use to that, I would leave the cage door open and stand next to the cage, he would run to the back at first but eventually he stayed in the front.
I then would go to touch him, he would run off. But then he got use to my hand and allows me to pet under his chin.
Now when I open the cage door, he comes to the front and hops right on my hand, wanting to come out and chill with me. When I go to put him back in his cage and I feel bad because he makes a u turn and climbs right up my arm, lol.