Bentley.MicroStation.AddIn

There is an entire forum dedicated to MicroStation Programming.

You can search there for answers to your question, and you can post your own question to get more answers. You will need to give them far more information than this, however. At the bare minimum, you want to tell them what version of MicroStation you are using and what language you are programming with. Code samples are also very helpful. The more detail you give about what you are trying to do and how you are trying to do it, the easier it is for people to help.