2)Open the mod you want change (e.g. description or add file), e.g. https://tlmods.org/en/mods/optifine/
4)Once you have added a file or added a description, pictures and more, click the button below "Submit for moderation".
5)Now wait until your element will be accepted or rejected by the administrator, the status of your edits you can see in your account "My added". Moderation can pass within a few days and if everything is fine, you will see your additions to the modpack system.
2)Hover over your account icon in the upper right corner.
3)Select "Add File" and then fill your future element with data, and send it to moderation at the bottom using the "Submit for moderation" button! Moderation can take place over several days, and if everything ok, you will see your additions in the modpack system.