1. Where are you?
2. What are you planning to stream (ground, tower, tracon, en route?)
3. Where are you located in relation to the transmitter(s) of the facilities you want to stream?
4. What do you have for equipment (computer, scanner, antenna, internet connection, etc)?
Once you have all these answered and everything set up, the streaming is relatively easy, just a small app you run on your computer.