Oh geez that was long time ago, but it seems what I say checks out. Tom said: But since the procedure for updating an existing sheet is different than submitting a new one... Well, to quote myself from 6 months ago: Andreas J. said : In some sense, editing an existing sheet is the same as as submitting a new one. Hopefully you'll see the similarities after following the steps at the end of my post. ...how exactly does one submit a new sheet image? With Sheet image, I assume you mean the preview image that shows up when you're selecting a character sheet for a new game(or change for an existing game)? And are you using only the GitHub browser for doing these things, or the graphical client or command line tool? Depending on which you prefer to work with changes who or what advice will be given. I'll asume you only used the broswer, so here comes. Browser(Advice on updating sheet preview image): In this example you'll do things exactly as I suggest them, so I'll assume you do this changes in your ' patch-3 ' branch, which is responsible for the first Pull request you made . I'm linking to exact places when I can. 1. Navigate to your patch-3'-branche's '7th Sea 2e' folder . 2 . There, select the 7th Sea 2e.png image. It should open the image for you, and just above the right top corner of the image, should have a " garbage can " icon, which you click on. This should bring you up a menu that says " Commit changes " 3 . In the headline you write "7th Sea 2e: Delete old preview image" Below there should exist a radio checkbox that is selected for "Commit directly to the ' patch-3 ' branch". You do not switch it to the other option that says something like "create new branch", that is unnecessary. 4. Then you press the green " Commit changes " button below. This chain of action should now remove the old image from the ' patch-3 '-branch you made the changes for. It updates automatically the Pull Request, as you had made change to the branch responsible for the Pull Request. You should be able to see the new changes added to the existing ones you made previously in your Pull Request from 'patch-3' . 5. Navigate again to the ' 7th Sea 2e' folder in your 'patch-3' branch, and the image should be gone. 6. press the "upload files" button(that should be on the top right side around where the 'trash can' button was ) 7. Now you can choose to upload what files you want, and you select your updated versing of the preview image you have made. Before you upload it, make sure it have exactly the same name as the old image . After all, we are replacing the old picture, (all functions and stuff that used the old image will use the new one, as long as you have a file with the same name and place as the old one). 8. in the title field, write "7th Sea 2e: Upload updated preview image" Below there should exist a radio box that is selected for "Commit directly to the ' patch-3 ' branch". You do not switch it to the other option that says something like "create new branch". We want to commit the changes to the same ' patch-3 ' we been working on this far. 9 . If things are right, press the " commit changes " button. It might need a few seconds processing, but the changes should have been done to the ' patch-3 ' branch. If you go look to the Pull request , it should look similar to this example I made . Afterwords: This same method can be used to add all the changes you want to do to the '7th Sea 2e' in one single pull request, which makes things much easier for those who are reviewing the PRs, as we as more easy for you to overview. Next, you should try to add what is missing from this pull request, namely the css changes and the new readme). Using the same kind of steps you should be able to figure it out, based on how you made changes to the existing sheet files and added the readme. Edit1: Fixed some links i had wrong.