If they can lift it, it will go in the nest. I like to give my Zebras small strands or burlap and shredded Kleenex to use for nesting material. It is important to make sure what you give them is not so fine that they can get it tangled around their legs or around the chicks, bird can die if they become too entangled in material. Eggs are usually laid one a day, incubation starts after the last egg is laid, and they start hatching about thirteen days later. Zebras can lay between one and 8 eggs.
Most nests have between two and five eggs though.
The female dose most of the incubating but the male will also take his turn on the eggs so the female can stretch, eat, and drink. If the eggs are fertile they will turn a darker color after the first week. If you can not really tell buy looking at the eggs if they are fertile or not, you can candle them. Candling eggs is really pretty simple but if you are very nervous about it, do not attempt it. To candle an egg all you need in a pen light or a small flashlight.