There's a huge range of these things. You might put an ad in Craigslist for someone with woodworking skills (and tools). But you should first have a pretty good idea what you want, like drawings to show exactly what you want. If the woodworker has to sit down with you and come up with a plan, he'll charge you a lot more.
If you plan to have a sink, stove, fridge, whatever, those should be part of the plan. You should do the research, pick what models you want and get all the dimensions. Or just buy them before you start!