To change the Welcome Page Content:
(This would appear at the top middle section of your site's main page)
1) Log into your store's admin section
2) Select the "Define Main Page" link from under the "Content Manager" menu
3) You will be taken to the "Define Main Page" section of your admin area.  An edit box, similar to a Word document with tool bars, will appear.  You can add your Welcome Page / Main Page content here.