To install car speakers, first disconnect the battery, disassemble the doors you wish to insert the speakers in, and remove the default speakers. If the holes left after removing the old speakers aren't large enough to accommodate your new speakers, cut properly-sized holes, install the speakers, and reassemble the doors. Finally, reconnect the car battery.
To find the ideal locations to mount the speakers, use the templates that come with them. Place the templates over the areas you would wish to mount the speakers, and check whether there are obstructions beneath or on these potential areas. Once you find the best places to mount the speakers, tape the templates on the areas, and trace the shapes of the templates using a pen. Place the door panels on a flat horizontal surface, and carefully cut out the shapes using a sharp utility knife.
Use the factory rubber tubing between the car doors and the door jambs to run the wires from the doors into the body. Depending on the design of your speakers, you may have to install them before or after replacing the door panels. Tighten the screws just enough to hold the panel in place so that you can test the new speakers. If the speakers work well, tighten the screws further, and finish reassembling the doors.