machine-learning,precision,recall,precision-recall

First of all, what you have written is not the F1-score. That is Precision! To compute the F1-score, set precision=TP/(TP+FP) and recall=TP/(TP+FN). Their harmonic mean is the F1-score. So, F1=2*(P*R)/(P+R). See this for further details. You can compute these values for each class and see how well you are doing...