Make your program work with other programs

Question

Hello everybody,
    I'm a newbie when it comes to C-Sharp but I'm more then willing to put the time in to learn. I have a question. Im building a program that stores my customers information. After I collect the info I need it to send the data to another program (ENCOMPASS 360).
I think I have to look at ENCOMPASS360's dll file, but Im not sure. Can someone tell me the best way to go about doing this? I would be willing to pay for the help.
I have already built the software to gather my customer info, I just need to know how I can pass it along. Thanks in advance.