Are you talking about having a portion of your main page be editable through the WYSIWYG editor built into vShare for the creation of HTML pages? If so, more than likely this will not be possible. What is possible is the ability to create a new advertisement section in which the person could edit the particular section of code and it would show up there. This would require them to know HTML to do, however, so it may or may not be worth it. I would NEVER recommend the use of SSI... ever. If you are going to use SSI, you'll get much better performance by using PHP instead.