Theme Boot Strap-adding pictures and text

Hi
I’m helping a friend make a site using the Boot Strap theme.

Here is a test page : http://eenmooieherinnering.nl/wordpress/?page_id=79

We want to add text under each picture and also to make a 2nd and 3rd row of pictures with text.

Can’t seem to figure out how to do this.
Any help gratefully received!
TIA