IF you mean C0ckatiels... the normal coloured greys are easy to sex; the hen has a duller face and spots under the tail whereas the c0ck has a black tail and yellow head with bright orange cheek patches. With the colour mutations, the gender is often hard to determine.
Presuming you have provided them with a nestbox, the hen will lay a few more eggs. Once the parents start incubating (yes, they both take turns) seriously, the eggs should hatch in 19 days or so. It is not easy to say just when they start incubating as they spend a lot of time in the nestbox before sitting in earnest.
Give the parents plenty of fresh greens, some soaked hulled oats and that canary softfood you can get from the petshop. Increase the food as the chicks grow as they are little gutses and will consume a lot more than an adult bird, until they are fully grown.
If the birds are chickens or something else, I've just had a little typing exercise. Loosens the fingers you know!