I'm an honors student in high school and I make A's and B's in my English class. However, today I failed my final exam for English with a 68%. So...

I cannot give you a definitive answer because I am lacking information. On the face of it, I would say it's unlikely you will fail.  What you must find out is if your grades are "weighted," which means that some grades are worth more than others, and you must also average all of the grades to see what your overall percentage is for the course. 

If the grades are weighted, this might mean that mid-terms and finals are worth more than quizzes or that neither has as much weight as assigned papers.  For example, I use a point system wherein quizzes are worth 100 points, but the mid-term and final are each worth 200 points. Papers have varying numbers of points.  At the end of the term, I add up all the points, and I find what percentage they are of a perfect total. If you could get a maximum of 1000 points, and yours added up to 900 points, that would be 90% and you would get an "A." 

If all grades have equal value, then you add up all your percentage grades and divide by the number of graded quizzes, assignments, and exams.  That gives you your average for the course, and that average is your final grade.  So, if you have two quizzes on which you got 90% each, two papers on which you got 95% each, and a final on which you got 68%, your average would be a bit over 87%, which would give you a high "B" in the course. 

I am sorry you failed the exam, but perhaps all is not lost!