This tutorial video provides a complete idea about how to coat your screen for exposing. All you require is that you should have a screen but make sure its mesh should have apposite stress, liquid emulsion, and potassium dichromate as sensitizer, pour sensitizer in the liquid emulsion after adding hot water in the sensitizer, then mix it with emulsion so that consistency appears in the emulsion mixture.
Now with the help of scoop coater you start coating your screen from both sides not too fast. You should stand your screen in erect position and it is enough to give a single coat from both sides. Once you have done this job then place your screen in some dark place for drying it. The screen exposing may take enough time because of emulsion application. After it has been dried it is ready to expose. The video link is sharing information about screen coating process at whole.