Summarize this article:

To open the screen, you need to move the window out of the way. Open the window by unlocking it and sliding the lower sash up as far as it will go. A double-hung window is made of 2 movable panels known as sashes. The lower sash is the bottom panel that rests against the window sill. The screens for double-hung windows have 2 tabs on either side of its bottom. Find the tabs with your fingers, placing your index fingers on their outside edge. In most cases, you’ll need to push the screen’s tabs inward so it can slide along the track. Use your fingers to press the tabs, and carefully slide the screen up to open it as far as you’d like. Once you are ready to close the screen, you simply need to slide it back down into place. Make sure to close it fully so the screen clips engage and lock the screen in place.
Raise the window’s lower sash. Locate the tabs at the bottom of the screen. Push the tabs inward and slide the screen upward. Close the screen by sliding it back down.