If you are new to MATSim, we suggest that you have a look at the tutorial "Getting started with MATSim". It will teach you the basics of MATSim and give you an introduction to the code. After that, there are the following options:

• Use matsim as a "user". For this, you need to prepare scenario data, modify the config file, and interpret matsim output. Look under "user's guide".
• Develop code using the matsim api. This means that you program, but your calls to matsim are restricted to "stable" calls to the matsim api. This is particularly interesting to people who want to use some matsim infrastructure for initial demand generation, but it may also be useful for people writing "modules" such as alternative mobility simulations or alternative behavioral modules.
• Develop code as a matsim developer. Since we do frequent refactorings of matsim, for this you need to be made part of the matsim repository. Please talk to us.