To edit the Agenda - First Day content, click the "VamTam Builder" link on the homepage: 

Next, click on the Tabs element > Firs Day > Edit Item: 

Here, you can delete the template shortcode and replace it with a different content: 

or you can edit the templates of the First Day and Second Day tabs in VamTam Builder > Templates: 

Edit the templates content according to this Guide to Vamtam Beaver Builder

You can edit the blue boxes background colour here: