As I know, most of us using gmax or 3ds max(payware version of gmax).
As
@Hector Lee said making an airport in this programs or sketchup, blender or whatever is very complicated.I apsolutely understand you becouse before 1 and a half year I was same as you, but everyday I was watching youtube tutorials, sometimes when somebody said to me, watch this tutorial, I was like, what this guy would help me with and I was closing the videos, but today I know that these tutorials was so helpful and useful.For beginning you can use this tutorial on how to make ground polygon, basic runway in gmax.
http://iblueyonder.com/wp-content/uploads/iby_ground_poly_tutorial.pdf Really Helpful tutorial, all beginners use this tutorial as primary tutorial.
When you learn how to make a runway, go ahead and see this tutorial
NOTE: READ THE WHOLE TUTORIAL CAREFULLY! I didn't read it carefullyy and I got so much problems, misunderstandings and something else..So I'm saying this expirienced.
http://www.fsdeveloper.com/wiki/index.php?title=Ground_Poly_Tutorial_for_the_year_2014+
This is a tutorial how to make a taxiway line or taxiway edge line (just increase the width dimension of the rectangle, everything is explained in this tutorial)
http://www.fsdeveloper.com/wiki/index.php?title=Taxiline_creation_with_GMax
In the future you'll want to put your own texture but it won't tile to the line and won't fit to the line correctly, there is a tutorial for this too.But, not now, I will give you whenever you want, but not now becouse you will be confused of everything

Good luck and ask me everything about your question! Wish you all best!
Teo