Just lean over the sink...look down at the drain and you should be okay. I even look more towards the overflow drain located at the front of the sink and that helps make it a little more comfortable for me. Just remember to keep your mouth open and breathe normally through your mouth. If you're really clogged up up there, the saline solution will come out of your mouth and can induce a slight gag reflex, but not too bad.
Karen, I would suggest you use it a few times yourself before trying to teach an 8 year old. Nothing better than first hand knowledge when trying to convey that to someone else. It does feel weird at first and totally unnatural, but you do get used to it rather quickly.
I tried using a small amount of salt, and it burned like hell for me. I just stick with the saline packets made by Neil-Med.