(A) Log in to 23andme and go to your "HOME" page by clicking your name here:
(B) Click the right-side arrow (double-circled in red), until you see "BROWSE RAW DATA" (also double-circled in red). Click "BROWSE RAW DATA" (or "Go" within that box).
(C) Now you will see the "DOWNLOAD" button (illustrated by a double red arrow in this screenshot photo). Click it.
(D) After clicking "Download", re-enter your password, secret question answer, and make sure the "Data set" drop-down form is set on "All DNA" as shown below. Then simply click "Download Data". Save it on your Desktop (as a .zip file).