harness for stereo silverado 2005

Hello, I know nothing about electrical wiring but I bought a harness to wire on the existing one with a new stereo. The people who sold it to me said it was 15 bucks and not 75 because there was something to do with a cable somewhere that had to be plugged and was not directly plug and play because of that... well, as I don t know how it works I can t even explain very well, but I trust you are experts here, so you must know... Anyway, they convinced me it was really easy and that I would do it easily with a look on the internet with people who have already done it, but I don t know really where to look, can someone please help?
thank you!

Kevin

That harness was 15 dollars and not 70 because if you use it you will lose all warning chimes and also lose your retained accessory power.  Meaning that now when you turn the key to the off position, the radio is going to turn off.  It is not going to wait for you to open the door. 

There should have been a red wire that came with the harness.  Connect it to the red wire of the new radio.  Run the other end of that wire to the fusebox located on the end of the dash at the drivers door.  Check the fuse in the top right corner of the fusebox, it should only get power when the key is in the on position.  This is the fuse you need to connect the red wire to.

Oh, I see. Thank you very much. Well you definitely aren't an idiot! :)
I need to connect the other end of the red wire to the fuse? But how is it done, connecting to a fuse??

I grind the corner of plastic off of the fuse to expose the leg of the fuse, then i solder the wire to the fuse.  Then using a volt meter, I determine which of the 2 contacts in the fuse box is the cold side (not the contact that has 12 volts on it)  Place the fuse in the fusebox so that the leg you soldered to is on the cold side of the fusebox.

thank you!