How to modify MGDRAW (usdraw entry)

Dear fluka expert
My simulation is a proton beam incident on a Lead-bismuth target.
I want to get information about the position, angle, energy distribution and weight. This result will be used to continue neutron transportation in other code. I need a customized mgdraw (usdraw entry) user routine.
I have never used mgdraw.f. and also deficient in the use of fortran. I need a specific material that explains the stepwise way to modify mgdraw file to suit my need. I read this part from the manual but I don,t seem to understand it well.

Dear @profftee97,

You could try to have a look at @cesc reply to this post: (p.n) reaction position-MGDRAW - #4 by cesc
You could use it as a guideline for your problem.