I have comments+ installed and configured, but the original

I have comments+ installed and configured, but the original wordpress comment form still showing on my site.

I make a try with facebook social plugin and it works ok.

I came back to comments+ and I can't make it work.

I see a section to configure Start and Finish injection hook, but i have no idea what to put there.

How can I know the start and finish injection hook of my theme?