Text continues moving horizontally rather than starting a new line in editable text field

I am trying to make a feed backbox for visitors on my website. I have made the editable text field and scroll bar and set all of my preferences, but when the typing reaches the border on the right of the text field it just continues to type further horizontaly. I can start a new line by pressing enter but I would like it to start a new line on its own when it reaches the boundary. Any help is appreciated.