Key Press Interaction while user is in Text Entry

So what i'm doing is creating a software simulation that includes Instant Messaging as part of the software. I would like the user to be able to type up a message and press enter on their keyboard to continue.

What i'm having trouble with is that in order to press the enter key to continue they need to click outside of the Text Entry box so that it loses focus, which isn't something they would need to do in the software.

Is there a way to allow the enter key to be used for a trigger while the user is still typing in the Text Entry box? Any suggestions for workarounds?

Thanks!