How do you get the headunit? how do u take apart the dash? sorry this is my first intsallation

If it's your first installation, either take it to a pro shop, or get the master sheets and install kits from Crutchfield.

If it weren't for the Crutchfield master sheets, I would have done serious damage to the dash of my Honda when dismantling it. There were some hidden things that I didn't know about, that the master sheet showed me how to take apart.