How do I format a disk on my Macbook Pro?

I see that your Question has languished for some period of time without response. You have posted your issue in Using Apple Support Communities whose topic is 'How to use this forum software's interface, features and/or how to find what you wish'. It is a relatively low traffic and inappropriate forum for your problem. I will ask our Hosts to move it to " MacBook Pro " where it may get a more rapid response from your fellow users.

Tell us your OS X version and what disk brand and its specifications.

ÇÇÇ

This is an external hard drive or what kind of disk?

In any case, using Disk Utility (Applications > Utilities), select the drive on the left and than choose partition. Choose 1 or more and name the drive(s). Choose Mac OS Extended (Journaled). Click on Options and choose GUID Partition Scheme. Hit Apply. Done. You can then use it for anything you want: drag 'n drop, Time machine, clones, whatever.