Restore Files from Seagate external hard drive?

I have a macbook (late 2009 version) and recently my hard drive failed. Before failing, I brought my mac in and a genius helped me do a time machine backup onto a 1t Seagate external hard drive (the external was reformatted for os beforehand). Now, I can't figure out how to restore my old information from the external onto my new, restored hard drive.