Dumb Questions About Reskinning A Character Sheet

So I want to run a Warhammer 40k re-skin of Band of Blades. Considering that the Band of Blades "character sheet" is actually a suite of half-a-dozen intricately interlocking nesting dolls that are pretending to be a character sheet, how do-able is this?  My plan was just to ctrl-f the text for elements I want to reskin and replace the Band of Blades word with the appropriate 40k re-skin, aka Panyar would become Deathworlder or something like that. Rifle becomes Lasgun. Render becomes Render: Champion of Khorn. That sort of thing. Be careful just to edit the player facing text, not the actual guts of the sheet so I don't break anything internal. Maybe swap out some of the art links to more 40k relevant drawings as a stretch goal if I wanted to get reeeaaally fancy.  I was hoping I could download the master file off of Github, edit it in the sheet sandbox, and be off to the races, but I seem to have hit a brick wall at step two of that plan. Here are my dumb questions: How do I get this sheet open in the sandbox so I can do my hamfisted edits?  Will I be able to run a game with a custom sheet using my re-skinned nonsense without having to reupload to Github? (I think that's only if I'm trying to make a custom sheet public? But as I type this I realize I might not know what Github is for.) Is this just not worth it and I should tell my players to just pretend their character sheets say "Carapace Armor" instead of "Heavy Armor?" Should I just start the CS Minor now...or? 

If you just want to reskin the character sheet and change player-facing names, that should be fairly easy. You dont need to re-upload a sheet to github to use it in your own custom campaign. To get stuff into the sandbox, download the html and css files from the github (if theres a translations file, you'll need that too - but not all campaigns have those). Then open a custom sandbox, and there's a poup form with a html, dss, and translations button. Click each of those (the last one is optional) and select the files you have stored on your hard disk. Then you'll be able to create a character and open it, and see what the sheet looks like. You perform your edits on the files on your hard disk (open them in an editor), then save them, and use the html and css buttons to update any changes, and the sheet will update instantly. When you are finished, create a new normal campaign, and in your character sheet selection, pick Custom Sheet. Savie it and select Game Settings. Then you will copy the contents of the html and css files into the appropriate tabs, and save it, and you have a campaign ready to use with your players.