Some weeks ago i recieved 2 promotion PCBs when I shopped at Itead... not knowing anything about them i googled and it was a project like that (not for mysensors though...)
I can only give you my personal advice.
Since you're on this forum, I expect that you are interested in sensors and stuff. In that case. Download this library and look at the examples. Try to understand them and try to adjust them slightly.
But, maybe it is a better idea to google "c++ tutorial". Arduino is C++ based. And this will definitely teach you the basics of the language.
Last, try to look at the Arduino website.
I had problems with the range with some outdoor sensors. I didn't read the spec of this one, but read on a forum that this one was much better.
But when I tested it, it was a uge different in range compared to the other unshielded with antenna.
Perhaps something similar to the power- or water flow pulse sensor example sketches?
https://www.mysensors.org/build/pulse_power
https://www.mysensors.org/build/pulse_water
Use a sensor such as this.
http://www.ebay.co.uk/itm/MPX5700DP-Differential-Air-Pressure-Sensor-Freescale-Arduino-MPX5700D-UK-Stock-/121626002591
There are heaps of similar sensors for measuring pressure ( or lack of )
