I want to add more vehicles and change the speed.
I used the command --max-num-vehicles 30 to try and start the simulation with more cars but for some reason the run time simulation never passes 50 or 60 active cars.
Also my simulation has traffic lights but they seem no to work properly because it only has 2 stages (Green light and Yellow light).
The purpose of --max-num-vehicles is to limit the number of cars not to increase it. The easiest way to get more cars is usually to define more traffic input either by using randomTrips.py with a higher period parameter (e.g. -p 1000) or by introducing flows with high counts into your route file, see also http://sumo.dlr.de/wiki/FAQ#How_do_I_get_high_flows.2Fvehicle_densities.3F.
Concerning the traffic light, you probably created a traffic light on a junction with just two streets. It is a known issue that sumo's netconvert does not add red phases here, because there are no conflicting flows demanding green time for them. If you are using the nightly svn version, you can use the --tls.red.time option to force a red time, if not you can edit them manually in netedit.
You may have to regenerate your map.rou.xml file in order to have more vehicles. As the response above said, use the -p 1000 to your randomTrips.py command, as an option
