My husband is starting work as a subcontractor. How much taxes does he take out of each paycheck?

We live in Texas and my husband is an immigrant from Brasil who just received his work permit from the US Dep't of Homeland Security. He is starting work as a subcontractor for a ceramic tile company. Neither one of us are experienced business people. When he starts to get checks from this company, they are not taking out taxes. He is responsible for taking out his own. What percentage and for what types of taxes does he need to take out. And does he pay it all at one time at the end of the year? What about paying his employees that do work for him? Do we take taxes when we pay them? I am his wife, am currently pregnant and am due in July so we will have a dependent. I work and make around 50,000 a year. I need advice!