Before you can drag a link, you must be able to see your bookmarks bar.
Windows/Linux: Press Ctrl + Shift + B
Mac: Press Cmd + Shift + B
You can bookmark a site in two ways using your mouse:
The Lock Icon: Click and hold the Padlock icon 🔒 located to the left of the website address (URL).
The Link: Click and hold a specific link on a webpage (like the one below).
While still holding your mouse button down, drag the icon/link down into the empty space of your Bookmarks Bar. Once you see a small vertical line or a "+" symbol appear, release the mouse button.
Drag the link below up to your bookmarks bar to save the Foundational Tech homepage: