OK Lorene,
I'll repeat some of Juhans advices with different words, and try to add a few extra cent's.
First I'd consider how the transformers should be used. As you have 4, I would suggest that you could sectionize your layout, so you may control a train in one part at the same time as a friend does it in another part. Catenary for e-loks is an option, but it takes some effort to get it working, and maybe you don't have that many e-loks. My main suggestion:
Three sections of track, for example line+2 stations or the like, controlled by each one transformer, the red output of the transformers used for each track. The last one used for all yellow cables to signals or turnouts. Lamps in houses etc could be connected also to this yellow, or optionally to the red output (but use yellow or for example orange cable); in this way you are allowed to dim the lights of these lights.
Which transformers you use for what is not so important; could easily be changed afterwards. 10 VA is weak but enough for one train. As said before, all browns together, including the transformers brown. And, the switch boxes with red and green buttons should be connected at their side with the brown cables.
Please keep in mind that when using sections of track, these transfomers should be in phase. At least here in Sweden the plug in the wall may be turned 180 degrees, which means that the AC of the transformer output is + when the other transformer was -. And it's not good to have it that way when the locos slider bridges two sections. Some countries AFAIK have asymmetrich plugs to guarrantee that the phase is the same; if not so do like this:
1. Arrange your transformer connection so that you can switch them off wihtout having to pull the plugs.
2. Connect the browns of all transformers together and put them on.
3. Set the speed dial to half speed on all.
4. Get a lamp or another simple means to measure voltage, and connect it between two red outputs. If the lamp is shining, the transformers are out of phase, if it's dark or only glowing, it's ok.
5. Turn the plug of one of the transfomers, and check again, until it's all ok.
Let's see, all browns together, the yellow cables together into the light trasformer, the red from each section together and to the corresponding transformer. The blues are left. They are connected to the boxes with the red and green buttons, pairwise. The red and green plugs here should mean red=turn,stop, green=straight,go. Could be tested by temporarily touching the any brown including the rails. When these cables are to short, my own special tip is to use extra cables with one red and one green plug; I always connect one green to one red, and the free end will have the right colour. The important thing is making up your mind and no cheating; in the long run it will make it easier for you.
Regards,
Lars Westerlind.