Carpenters produce items out of wood. They construct beds, bins, barrels, and all manner of other furniture. They can also create structures such as walls and staircases. A carpenter's skill level affects the speed and quality of his work.
To employ a carpenter, create a task at a carpenter's workshop or designate a construction using logs.
A migrant carpenter may bring an axe with him, despite not having any skill in wood cutting.
More times than not the migrant will literally throw the axe aside upon entering your map, make sure you have a weapon stockpile assigned so one of non-migrants can go and haul it to your fort.