To put a message behind a picture is really easy:
Insert an emoticon into your message.
Go to the bottom of the message screen and click the box beside where it says "Use HTML to create your page."
A page of code will replace the text editor. Read through the code until you find the place where it reads:
<DIV align=center><IMG style="WIDTH: 126px; HEIGHT: 189px" height=455 src="#/isapi/fetch.dll?action
After the part where it says IMG etc . . height=455, type in: alt="your message here".
<DIV align=center><IMG style="WIDTH: 126px; HEIGHT: 189px" height=455 alt=" Watch your step, it is wet here ! " src="#/isapi/fetch.dll?action
Go back down to the bottom of the page, and uncheck the box where it says "Use HTML to create your page."
Finish your message, and click Send.
To have a picture link along with the mouseover, in groups click on the picture and then click on the globe with glasses in the toolbar, before the tables icon. Insert the link in the appropriate box and create.