Follow the instructions in the article Access RDB: How to create or update an email signature.
Should following this advice not result in a signature strip that looks correct, it may be too complex or have too many images. The signature file can be imported instead, as follows:
Go to Options and then click User Preferences.
Click Letter/Email.
Click More and then click Import.
Over-type the folder location text with %appdata%.
Navigate to \Microsoft\Signatures.
Select a signature file to import.
If a suitable file cannot be located, your IT team may need to simplify your Outlook signature strip for you.