Dead easy to fit to a current Fiesta. You have this model?
I looked at various camera positions but didn't much want to drill steel, so I chose the black bit of the bumper where it's concave.
I drilled the plastic bumper and opened up the hole with a file. No need for accuracy as the camera's flange covers any slight mistakes. Behind that black bit of the bumper is a reinforcement and I've used this with a tiny bracket to make the camera 'look upwards' slightly as it's rather a low-down fixing point. If you really make a hash of things then a rubber grommet will let you cover the hole.
The camera comes with two wires, one is a power feed and the other is the signal feed. Take off the off-side real lamp cluster (removing the boot carpet in the vicinity is the difficult bit) and wire the camera to the reversing light power lead. Run the signal cable into the car via this rear light cluster and from there to the boot, past the rear seat and up to the centre console under the driver's seat.
The monitor's power is taken from the fuse box which sits behind the glove box (I chose to use the reversing light's fuse), and it's a simple matter to hide the wire between the top and bottom half of the centre console as it goes to feed the little 4.3'' monitor. You can just see this wire leading to the monitor in my picture, but you could do an even neater job by drilling a hole for the cable in that pretty useless cubby hole that the monitor now blanks off.
The monitor is a bit low in actual practice - it would be grand in the info screen's position and you can get 'fold-down' screens if you fancy going that route. Selecting reverse powers the camera and the signal sent to the monitor turns that on - so everything is automatic and dandy. The camera works in very low light though of course your reversing lights help a lot.
And that's about it. You'll still use your door mirrors, but the camera will let you get to with a few inches of the car parked behind you, far far closer than bravery allows. What would have been good is if the camera's image went out of focus when objects were 12'' away, say, But the image is sharp from 1'' to infinity amazingly, so they've missed a trick there.
Need more info? Just holler.