To insert an equation into the library, simply click the "Add to Library" button. The equation currently displayed in the main window will be inserted into the library.
Deleting equations
There are several ways to delete equations from the library. The easiest, if you have a multi-button mouse, is to right-click on the equation you want to delete. If you don't have a multi-button mouse, you can control-click on an equation to delete it. You can also shift-click on an equation in the library to select it, and then press Delete to remove it.
There is no way to Undo the removal of equations!
Changing the order of equations
To change the order equations are displayed in the library, shift-click on an equation in the library to select it. Then press either the Up or Down arrows to move it. If you have a mouse with a scroll wheel, you can move the equation with the scroll wheel.