How do I connect PVC branch piping to steel piping

DWV or pressure? If drain (and your local code allows it) you can use a Fernco or equivalent connector if it is in an exposed location. CHECK YOUR LOCAL CODES. If pressure, what size and what type of end will be on your "steel" pipe? Threaded? Spigot? And of course I expect you to know all the norms of support, venting (if applicable), sizing and all the other requirements of plumbing installation.

Really your question is too cryptic for a good answer.

How do I connect PVC branch piping to steel piping

Hi Karen,
You weren't clear so I'm going to assume that you wish to convert from a galvanized iron pressured hpuse to a 1/2" PVC branch line.
Am I correct? Post back with more details. Regards, Tom