If I want to marry a man from another country here on a work visa, what do we have to do to get married and will he have to return to his country for a while?

It is fairly straightforward. In order to get married you need to contact the local authorities as if you are marrying someone from the US. It is generally done on a county level. Once married, we need to file an Alien relative petition and the adjustment of status documents. He will not have to leave the country - I can get him a green card here in the US. I would be glad to help. Please contact me directly at meltser@bmlaw.com