In Boost the pagelayout files are in the boost/layout directory and the mustache templates are in the boost/templates directory. Altering these is not as easy as the older themes were.
As an Administrator you can set the calendar block to the top of the middle column of the Dashboard page, but you probably know that. Indeed it is perhaps easier to make the calendar block be at the top of the right column which at this moment in time is the only other block region it can be fixed permanently.
The alternative way would be to use Richard Oelmann's method of adding a new block region to the Boost theme? The trick there would be to copy Richard's code and perhaps instead of adding to; the Boost theme (which is Moodles Default theme that is constantly going through changes), and use the Photo theme instead, as that is a direct copy of the Boost theme with added options to add images to different pages.
I am sure we can help you achieve that goal?