And haow can I change the consists?
You must manualy (without using a program) edit the scenery (.scn) file. The consists are usually on the end of the file. I think you can easily understand them. They look like this:
node -1 0 SN61-86 dynamic PKP\SN61 SN61-86 sn61 0.0 headdriver 3 0 enddynamic
Now the "translation" of the code:
node -1 0 [name of the vehicle - it will be shown in start.exe] [path to the vehicle dir] [texture] [name of the chk and mmd file] 0.0 [headdriver, nobody (you can't drive it), reardriver)] [type of coupler: 1-mechanic 2-pneumatic 1+2=3, so your vehicle will be joined with another with a pneumatic and a mechanic coupler, 7 is a type of coupler that will make two locomotives work while driving using the front loco (you must change the "headdriver" parrameter in the 2nd loco to nobody so there won't be anybody in the 2nd loco)] 0 endynamic
Now you should undestand