Season 5-Finale. I need somethings explaining.

Alright, when you watch it, it is meant to be confusing. Jenny will not kill "The Frog" who is La Grenuelli who is Rene Benoit (sorry for misspelling stuff). You are lead to believe in another episode (I believe) that Gibbs killed Rene. Jenny definately didn't kill Rene, though, and you can be sure of that through her reminiscing of how she wishes she had killed him. If you go on surfthechannel.com and look up NCIS, you can rewatch the episodes and watch the S5 finale as well as other related ones. Or, if you're just looking for a synopsis, go on wiki and look at the episode guide for S5. That should clear up the issues. Sorry if this isn't helpful. It is shrouded in mystery even though it's been totally not mentioned in S7 anymore.