If you got Version 10 of DL before 2/6/2017 , you should download the Free Supplement to Version 10. If you acquired or updated to Version 10 after that date, it is not necessary to download the supplement.
If you have not yet updated to Version 10, click on Update to Version 10 rather than downloading the supplement, since the supplement is not compatible with older versions of DL.
When you download the supplement, a file named "DL Supplement to Version 10.EXE" will be downloaded. We suggest that you save this EXE file on your computer's desktop or some other location where you typically save downloads. After you have saved the EXE file, you can double click on that EXE file to install the contents of the supplement over top of the Version 10 of DL on your computer (most users have DL in a C:\DLWIN folder). After you have installed the supplement you will see the 2/6/2017 date on the "splash screen" of text displayed for a few seconds when the DL program is first started. The splash screen is a picture of a court house with four lines of text; the date of the supplement is on the last line.