First question is, which one to get?
It's also sold under other names, but the most popular one here seems to be the Tekonsha "Prodigy". I must recommend to stay away from the cheaper "time-delay"-type controllers, because in an emergency you DO NOT WANT to wait for any time-delay. (If you need to stomp your brake pedal HARD, you want the trailer brakes to activate IMMEDIATELY, not slowly "ramping up" to full power.)
There's a new model of the "Prodigy" called Tekonsha "P3", with a pretty little screen on it. (Costs more.) And there's a competitor called "Valley Odyssey 58210" it's very good too. Among those "time-delay" models which I don't like are Draw-Tite "Activator" I and II, and Tekonsha "Powertrac". I just don't think it makes any sense to save $20-30 on the brake controller while increasing the risk of an accident to your $20K trailer (and $$$$ TV, and PEOPLE INSIDE).
There's a couple of controllers which actually measure the position of your brake Pedal, instead of working from TV brake voltage, and at least one which plugs right into your hydraulics and measures pressure. But installation is weird, and you're gonna be in trouble if you have a problem on the road: in contrast, every trailer/towing shop in the Country has a "Prodigy".
Second question is, how to install it?
If you're lucky, like I am, then your vehicle has a socket already present, under the dash, to plug in the Tekonsha-sold "wire harness" adapter. (I was even more lucky-- in fact the Tekonsha-provided installation pictures showed installation in a Toyota 4Runner!) There's movies of a Ford F-150 installation on the Internet. This is a 3-minute DIY (NOT 5 minutes-- definitely only 3 minutes). They make harnesses for just about every TV,
http://www.tekonsha.com/tbsabrakeconwireharn.html
If you're NOT lucky, there's some 3rd party wiring products, and it might involve actual wiring (back into the engine compartment). You might want a trailer place to manage that. But it's extremely unlikely. If the Tekonsha harness fits, do it yourself-- the dealer has to charge $40-50 just to write up the order for the 3 minute job.
BTW, if the vehicles harness has more plugs than your Tekonsha adapter actually uses, don't sweat it-- the extra one (or two) are totally unnecessary. My 4Runner socket has 6 leads, Tekonsha only uses 5, everything works fine. (In modern trailers, that lead is provided by the bargeman electrical connector.)