Open your HTML email signature file in Notepad if running Windows, or Text Edit if running macOS.
Press Ctrl + A to Select All, followed by Ctrl + C to Copy the code.
If running macOS, using the Cmd key instead of Ctrl.
Switch across to your web browser and your LionDesk account, then from the top right of your screen, click on your Profile icon and select Profile.
Click inside your signature field and a toolbar will open above with a range of buttons. From the top left, click the Source button.
Paste your copied email signature code into the window and click OK.
You will see your email signature appear in the box now, likely with borders around it. Ignore these as they're just the table and cells being outlined and will not show when your email is sent.
Click the Save Signature button to the left of your signature box.