Click on Mail in the left pane and ensure that “HTML” is selected in the “Compose in this message format” section in the right pane, then click the Signatures button.
Click New. Type a name for the new signature, and then click OK.
If you just want to change an existing email signature, select the signature you want to edit.
Click in the Edit Signature box and paste (or press CTRL+V) your new or updated email signature. On the right side of the window, select if the email signature should automatically appear for new messages and/or replies and forwards. Click OK on all windows until you are back at the main Outlook window. Click to create a new email and check out your new signature!