and good luck with what you do enjoy modding ;)

yes i do its not a vid but this will help

what you will need:
a image editing app
and the ability to rename files from the editing app to .png or .jpg depending on what you are changing

for windows:
press the home button then type in run after doing that put in run %appdata% in the folder open .minecraft go down to mods and open mcheli go to assets/textures/helicopters and right click and choose open with then your image editing application the from there do what you want then you can save it 2 ways way1: go to file export and export is as needed so .png sometimes .jpg then move to the texture/helicopters folder and tell it if its still in there to overwrite file way2: save as normal open where you saved it and change the file name from editing app for me it would be .pxd change that to .png and if it says if done file may be unusable do it anyway then move to texture/helicopters.

for mac:
open a finder page and click go in the top left once open hold alt and click on library then go to minecraft/mods/mcheli/assets/textures/helicopters then find what you want to edit right click and choose open with editing app same for windows as saving 2 ways export or change name manually then move to file location