Caring for Zebra Finches?

I have 2 zebra finches a male and female. I have had them for 2 weeks as they were needing to be re-homed from an elderly man. I had them 5 days when I discovered an egg in one of the feeding boxes which they tend to sleep in. She laid 4 eggs, but after several days of her sitting on them she managed to get them out of the box and unfortunately they broke when landing on the bottom of the cage. For the past 2 days she has continued to sit in the box like before and she has taken to fighting with the male as often as today. What should I do as I am a complete beginner.