I have a HW problem which I have to program using fortran. I checked online to try to learn how to do this, but I found several versions of fortran. Which one should I use? Also I want to assemble this code. Does anyone have any idea how to get the assembly?
Fortran is a standardized language. The Standard was developed over the years with the more notable versions being 77 (therefore Fortran 77), 90, 95, 2003 and 2008 (versions roughly tell the years in which the version of the Standard was done).
As far as "assembling the code" (I have no idea whether I'm reading this correctly ??) you need a compiler. There is a pretty good list here. Each one comes with a manual that covers options and switches and the note which version of the Standard it supports (currently there is no compiler which fully supports f2003 but there are a few which implement a lot of features from 2003 and 2008).