first you will need to learn how to program (unless your making very simple
stuff in which case try Scratch)
I would Recommend learning HTML first as its used to make web pages as is
very useful to know but is also a very good first coding language
for HTML all you need as a development tool is a text editor and a web
browser just make a text file with the file extension .html and open it in
your web browser
You can find a good tutorial here:
http://www.w3schools.com/html/default.asp
after HTML i recommend learning C it takes time to understand a A LOT of time
to fully understand but you will learn loads from it so even if its just the
basics C is very good to know
(if you ever find C too hard i recommend learning lua)
you can find a good C tutorial here:
https://www.youtube.com/playlist?list=PL0170B6E7DD6D8810
as a huge amount of programs are written in c so you will be able to
understand them also its very very similar to the language C++ which is used
a lot in video games so it will be easy to learn C++ afterwards but i
recommend learning C first as its simpler
its very easy to make C programs with trisquel(with all free software) just
install the gnu c compiler
sudo apt-get install gcc
and then from the terminal run
gcc [MYFILE.c]
if you need any help doing this just ask
after you have learned C as a introduction to graphics (kinda important for
games) i would recommend learning SDL2
you can find some very good tutorials here:
http://lazyfoo.net/tutorials/SDL/index.php
Good luck programming!