First you MUST have the bird’s trust you if the bird does not trust you.,
Go to the bird slowly you do not want to scare him/her then put your hand in the cage and talk softly.
Put your hand on his/her chest and pet down to the good foot and say “up” and at the same time softly push the bird on to your finger/fingers depending on size of your bird.
Hold your bird’s wings so he/she does not fly away.
Repeat until learned by bird.
Work on that before beginning this.;