Yǎnyuánmen zhèngzài hòutái shàngzhuāng, zhǔnbèi wǎnshang de yǎnchū.
The actors are putting on their makeup backstage, getting ready for the evening show.
Tips
usage
The opposite is 卸妆 'to take makeup off'. Skin that holds makeup well is 好上妆, and everything done before it, such as moisturizer and primer, is 上妆前 prep. 化妆 is the general word; 上妆 is common in beauty tutorials and backstage.