The Clipboard is part of Windows and many programs accept input from the Clipboard.
To copy the graph to the Clipboard, click Edit at the top of the CalGraph window and then click Copy Graph to Clipboard. Open the program you want to copy into; it probably has an Edit button at the top of its window. Click that Edit and you will see Paste as one of the choices. Click Paste and your graph is now in that program. You can do whatever that program allows you to do to it.
It is amazing how many programs allow you to paste a graphic into a file. Word processors (like Microsoft Word), sophisticated graphics editors (like Adobe Photoshop), simple graphics editors (like Paint that comes with Windows), even spreadsheets (like Excel), all accept CalGraph graphs.
If you get an error response, or if the Paste option is greyed out or missing, it means the program will not accept the graph. It may want you to open a file first. Open a file and try to paste again.
A suggestion: I find that the size of my graph makes quite a difference to the document I put it in. Sometimes if I copy the graph into another program and then pull on the corner to stretch or shrink it, the graph seems to lose a lot in quality. To avoid this, I adjust the size of the CalGraph window, which adjusts the size of my graph and then Edit > Copy to the Clipboard and Paste into that other program.
If you want to use the graph with a program that will not accept it from the Clipboard, you can try to Export the file and then import it into your program.
If you have a number in the result box, you can copy the number to another program.