Fischer's defense 5.Bc4

Hi kvnsndrs87--you have the upper hand since you've guarded your extra pawn and white's knight is kept out of e5/g5.  You want to maintain that structure while looking out for h4 or e5 on white's part.  ...Bg7 is a great move here, combined with Nc6 to pressure d4 and allow ...Ne5 against d5?.  Your c8 bishop will go to g4 when it gets the chance (or possibly h3 is white tries g3) and that will clear the way for you to consolidate with 0-0-0.  The most natural move that runs into trouble here is Nf6; it encourages e5, breaking open the e-file, as well as h4 now that your queen's communication with g5 is interrupted.  Get your queenside pieces out first and you'll be okay here.

i am no expert (actually quite far from it!) but I do have plenty of experience in the King's Gambit (my personal favorite opening). 

Fischer's Defence. IMO is a bit slow of a defense to the King's Gambit which gives white way too much for the pawn, g5 however forces white to prove that not only was the sac worth it, but prove he can do all that mumbo jumbo he claims (develop rapidly, control the center completely, exert pressure along the f-file and occasionally e-file, and hinder black's development). h6 is an espessially slow variation. Challenge white, Bc4 actually invites g4 virtually winning a piece from white, however white can develop a very nice attack right out of the opening, if this is played. I Highly recomend that a developmental move be played, for example, Bg7. which eyes the center, challenging white, begins preparations to castle short, and allows Ne7 where the Night isn't able to be kicked and keeping plenty of scope for the bishop and eyeing the d5 square which you will want to place a pawn on after playing c6. 

That is the advice I would give to anyone having trouble with the KG, and this is coming from a KGer, so if you don't trust it, look at how often people mention d5 as a major move for black in almost every open game gambit. It is a very potent move and not to be taken lightly.