How to create limited time-span overwritten backups

Hello!

Please excuse what may be a very simple, yet confused, question from this backup noob.

We are backing up a Windows 2008 server (running MS SQL) to an external hard drive (LaCie Quadra USB 4 TB).

We would like to create a recurring backup that performs backups four times a week for a month then overwrites the backups. (This is to avoid filling up the hard drive with more than a months' worth of backups.) We looked for ways to do this but could not find (or figure out) how to do so.

Is there a way to do this? 

Thanks!