Hi.
I want to paint my h3 to matt black but.. i dunno how to take off those parts marked red on the picture.
heeelp :/

 

Pretty sure there are screws in the door jambs and underneath in the wheel wells...

 

Start by removing the round clips under the fender. The pic shows a couple of the clips. ONce the inner fender is loose/removed you will be able to see under the fender flares you want to paint and there will be more clips holding that piece on. They are black plastic and will probably break easily if you aren't careful.
I'm not real sure about the hood pieces. If you can, take pics of the process while your doing it and post them here for the next guy.

 

The hood 'air intakes' can be removed by grabbing 2 opposite sides, and giving a quick jerk straight up. They have retainer pins, (nothing you need to remove), holding them in place.