How can I use hyper-V in windows 7 on a Macbook pro using Bootcamp?
Hyper-V isn't available for Windows 7. You have to install at least Windows 8 Pro/Enterprise or Windows Server 2008/2012. (Source)

You might install Hyper-V Manager (probably you did already) though. This application allows to manage Hyper-V hypervisors installed on other computers meeting the above mentioned Operating System requirements.