What does it do? You can easily imagine that it is tedious to have to type in complicated equations and to arrange interesting displays of the graphics. You will usually want to save your work so that you can pick up where you left off. How do I use it? You may write save your work in a file using the following steps.
Once you have saved your work in a file, you may rewrite that file at any time by choosing the Save item from the File menu. Doing so avoids all of the tedium of dealing with the 'Save As' dialog box. The latter procedure also works when you read the current setup from a file.