How do you add a build agent to another machine

Hello.

I have TFS 2013 running on a Windows 2012 server (Machine A).  I would like to have a build agent running on another machine (Machine B) so that build operations do not put a load on Machine A.  How can this be done?  Can this be done with the Build controller running on Machine A so that Machine A's controller controls the build agent on Machine B? Also, can Machine B be a Windows 8 workstation on the network or does it have to be another Windows 2012 server? In this regard, what is the maximum number of users a build machine configured as a Windows 8 desktop can support before having to use a server instead of a workstation for the build process.

Thanks in advance