Thread:Project:Support desk/Change the size of a "dashed box"?

Hello. I am a noob so please bear with me. I'm doing some formatting on pages for my company and I just learned how to make a dashed box like this: Hey look! A dashed box!

Two questions: Is that what they're called? A "dashed box"? And more importantly, can one change the size? I would like to make it less wide.

Thank you.