How many additional valence electrons does fluorine need to have a full valence?

I believe you are talking about fluorine. If you are, F needs one more electron to gain a full shell.

If you go to WikiAnswers for this information, that is counterproductive, because there is a much better way to do it. Look at the Periodic Table. Groups IA through VIIIA tell you what you need to know. IA has one valence electron, IIA has two valence electrons etc. Fluorine is in group VIIA and therefore has seven valence electrons. All atoms want eight, and thus fluorine is in need of one more.