If the exhaust manifold is leaking, you will need to replace the gasket if it has one or maybe install one if it doesn't. But, usually the cause of a leak is a broken manifold stud and/or a warped manifold. You'll have to remove the manifold from the head or maybe from the car, either way. You can get a machine shop to check for warping or you can try just a gasket if one's available and you feel lucky. A broken stud must be extracted and that's a tricky operation, someitmes.
Here's a directory link for you: