Im not entirely sure what this is actually called which is probably why I havent been able to find help elsewhere.
Basically when I hover my mouse over my image I want it to tell me what it is, for example tell me that, the image is the delete button.
"<td><a href=$del><img src=\"del.png\"></td>";
You can use "title" attribute, example:
"<td><a href=$del><img src=\"del.png\" title='EXPLANATION HERE'></td>";
In this case the text "EXPLANATION HERE" will appear when the mouse is over the image.