Outlook
New Outlook and Outlook on the web
Copy your Sigxel signature. Open Settings → Accounts → Signatures, select the account, and create a signature. Paste into the editor, choose defaults for new messages and replies, and save. Older web interfaces may show Mail → Compose and reply instead.
Classic Outlook for Windows
Open a new message, then Message → Signature → Signatures. Add a signature and paste it into the editor. Select the email account and defaults for new messages and replies. Confirm with OK.
Check the result
Send a test message. Some Outlook versions change fonts and image corners. Your desktop and web installations may need separate setup.
Source: Microsoft's Outlook signature guide.