A chalazion is an inflammatory response that results from blockage of the duct of one of the Meibomian glands; these glands produce an oil like fluid that acts as an eye lubricant and are located just behind the eyelid. Less common causes are infection (namely by a bacterium called Staphylococcus) .
Sebaceous glands are the glands that produce oily material to lubricate the skin. Depending on which glands are blocked, they can be superficial or deep.
Management is usually conservative and consists of warm compresses (a wet sterile gauze, as hot as can be tolerated) applied for 15 min 2-4 times daily in addition to gentle massage. This can melt the lipid secretions thereby inducing resolution of the ductal blockage which underlies stye formation. Topical steroid application (drops) is useful to take care of the inflammation. Topical antibiotics are not always recommended but can be helpful if an infectious process is suspected.
Incision and drainage (شق و تنظيف) is reserved for cases that don't respond to the above mentioned measures and according to the ophthalmologist's clinical judgment.
You will need to wait till the the size of the stye shrinks significantly and that there is no more redness before you can apply make up onto the affected area. And when you do, be careful not to injure it.