Your signature can be turned on in the Settings menu. Simply type in the content for your respective signature. To add any images you must know the web url of the saved image to insert and insert using the picture icon:
Type in the respective url in the pop up box.
Some notes on your signatures:
- If you have multiple accounts you are sending from in your Google Apps mail account, you can create a unique signature for each. When you select the respective FROM address, the respective signature will display.
- You can modify any content in the signature as an edit before sending.