Setting Background Images

I want to model a car and I want to set a background image but I can’t find the thing for it. Is it possible to have three so that you can have a view of the front and side and back.

You can find this option in the ‘View’ menu:
‘Background image’.
Click ‘Use Background Image’, then choose your file.

Oh, and regarding the three images…
Simply split your 3D viewport into three areas and set different background images. Of course, these images should then correspond to the views (top, left right, whatever) that you set in these areas, respectively.

one more thing with the top image blueprint that I have, I’ts the wrong way round and I need to rotate the view bye 180 degrees but it just disappears will i have to manually flip the image?

“Rotate the view by 180 degrees” around which axis and in which view?
Do you mean, you set ‘top’ view and the image appears upside-down?
In that case, yes, you should manually rotate the image before loading it into your viewport.

Generally, the viewports only show the image background images, when you set one of the ‘standard’ views: top (7), bottom (ctrl-7), front (1), back (ctrl-1), right (3), left (ctrl-3). When you manually rotate your model, the background images disappear (as they wouldn’t line up anymore anyway).
Also, the background images have to correspond to the correct rotation in each of these views: e.g., in the ‘right’ view the bottom of your viewport is the ‘bottom’ of your model (naturally), in the ‘top’ view the bottom of your viewport is the front of your model, etc.

And, while you’re in your image manipulation software, see to it that the images/blueprints line up perfectly pixelwise. I.e., the pixel-width of your blueprints in ‘top’ and ‘front’ view should be the same - same with the pixel-height of your blueprints in ‘front’ and ‘right’ view.
(If they’re not equal you could always use the ‘size’ option in the ‘Background Image’ dialog in Blender, but it’s easier the other way.)

shamless plug …