Test the terminals with a small 12 to 16 volt light bulb. Once you know which are live and ground, and which two are the speed control knob side, the one live wire goes to the center rail, and the ground wire to the rail. The other two are for accessories and lighting.

Ok, I didn't know that Alan. So Logically, if the two outer rails are isolated from each other to allow two trains to run simultaneously, a two pole switch, or a second speed control would be needed for each. The first using one transformer, and toggling between the two Locos. The second just a rehostat connected to the same transformer, or a second transformer?
Still, he should be able to run one train with what he has.

And 2 pictures of the manual of my 5599 Trix Express transformer

Keep in mind that your red 5529 transformer is a very light transformer, intended for the small steam loco BR80.
It supply 0.1 Amp, most Trix Express loco's don't run on a 5529, they need way more power than the 100mA of a 5529 transformer.

I use the 5529 only for a single small lightbulb in a modelhouse, not for running trains.

Marco