please help me,ima major amateur about car audio

so i have this alpine deck CDE-102 with a usb port and its one of the newer ones
and rockford fostgate R1653 6 1/2 speakers

my EF sedan didnt come with rear speakers but it did come with wires so i cut holes in the rear panel and the plugs wont work with the rear speakers.
the plugs work i tested them with my front factory door speakers.so im guessing its the connectors?

and i have this crappy pioneer cd deck in my EF right now and want to replace it with my newer alpine deck.how do i do this?

i called a few shops but they say itll cost 100-130 to install both.
so i thought i minus well DIY, please will greatly appeciate some help.
i keep reading that stereo harnesses are like 15bucks,so ima look into that.

 

You should already have a harness if the person that did the pioneer did it correctly. You can just pop out the pioneer, unplug the harness from the car's harness, then cut it off from the pioneer and match the wire colors and solder (preferably) or use screw couplers to connect the wires from your new harness to the old one. Then just plug the alpine harness into the car harness and slide the deck into the slot.
What "plugs" are you talking about?

 

the factory connectors to the factory speakers didnt work with my rockford R1653 speakers

and thanks ima look into that harness thing right now

 

Cut the connectors and solder the wires to the speaker inputs.

 

What year is your civic?94