Thanks for the reply, it has lead me to the solution. I would like to clarify for anyone else looking for this answer.
First, yes you are right that home sharing must be turned on, on the Apple TV and the computer. The links you provided showed how to do this. Once this was done I opened the Apple TV app on my Mac and imported my videos into the folder "home movies." I had to add to the list on the left as it initially was not showing up. I will also note that I needed to convert my file as it didnt seem to want to accept an AVI file. One this was done I went to my Apple TV and went to the "computers" app and it was in there.
Seems to be working!