Some examples of IDEs are brackets (http://brackets.io/) and notepad++ (https://notepad-plus-plus.org/)
These are both completely free, but serve different purposes.
Brackets is more web oriented, whereas notepad++ is effectively an everything goes.
One of the most useful features you should look for when considering an IDE is auto-complete (referred to as Intellisense by Microsoft).
It is very useful because when coding, you won’t be able to remember all of the syntax, and as such, auto-complete steps in the way and helps you out. Further more, it speeds up coding by a lot because certain syntax can become extremely long, and have to type it multiple times will get annoying.
It should be noted, that sometimes IDEs have roughly the same features & thus it boils down to preference of what you find the most comfortable.
As a general statement for when it comes to programming, don’t think googling is a bad thing, this is how you learn better algorithms & structures and solve your errors. You’ll notice that most of your answers will come from stack overflow, our holy grail of programming.
Some related links:
https://wiki.beestation13.com/view/Understanding_SS13_code (Basics)
https://wiki.beestation13.com/view/Downloading_the_source_code#Hosting_a_server (You will need this to test your additions)
https://wiki.beestation13.com/view/Coding_Standards (Probably the toughest challenge there will be to overcome)
I wish you the best of luck.
Considering Kerbin_Fiber is looking after this thread, I’ll leave this post up to his discretion entirely, whether to remove it, integrate it into his own or keep it.