Welcome to the forum.
What's the bird's name and how old is he?
Generally one of the first steps is step-up or stick training. However depending on his current behavior (reactions to people) there can also be a 'zeroeth' step: building trust.
Give him some time alone in his cage just getting used to the routine of the household. Let him see that you are the one who feeds him and changes out his water - try to make a schedule or predictable routine out of this. Talk to him calmly in the cage and offer treats (fresh fruits or nuts can work well). Only allow him to have the treat if his is calm. If he tries to bite, fluffs up aggressively, or makes any other display take the treat away.
The key in this stage is patience and time.
When he is comfortable with you being around his cage and offering treats then you can move on to stick training / step-up training. You can likely find many descriptions of this online, but I'd be happy to describe it if/when needed.
Good luck, and keep us posted.