Hi there,
Don't worry, inserting a line is simple. You can do it in a few easy steps and even move the horizontal line to where you want it in the document. Just watch this short video tutorial from the Office Help page to get step by step directions:
http://www.woopid.com/video/1179/Ins...rizontal-Lines.
I hope this helps!
Isabella
MSFT Office Outreach Team