First of all, if your car still has the original radio you'll need one of these
. To make the new one fit nicely with the centre console.
You might also need this
To remove an original radio (Alpine unit) stick two thin screwdrivers in the holes top-left and top right, and it should pop out.. If you already have an aftermarket headunit you need the correct tools for the brand.
Once the old radio is out disconnect the wiring, and remove the mountingframe.
Put the new mounting frame in with the facia adaptor.
Now for the wiring... Antenna and speaker ISO will plug straight in (might need the adapter for the antenna).
The power ISO is a little different. If you have no problem having to turn the radio on/off manually, and having it on "standby" so it can be turned on without the key in the ignition just plug it in and be done with it.
If you want it to turn on/off with ignition, have a look here
When wires are connected push radio into mounting frame - click - and you're done.