In your project go to project tab and click on export and then add an export as html then export and make sure that you exported it in a folder so before verything create a new folder in your project's whole folder and name it whatever you want then export as html in that folder so after exporting it enter ur project's whole folder and open the folder that you made(the one you exported the game to) then depending on whatever your main browser is find the file that is html it can be any browser's html then rename it to index since the pc will add .html already so if you make it index.html it will be index.html.html so then return to the project's whole folder and right click on the folder you exported your game in and hover your mouse cursor on send to then click on compressed zip file. now in itch.io upload that zip file. the name and all the other stuff i think u know them but to make sure u know everything try to export any game now. i wish i helped. i know its very confusing in text like this so if u didnt understand go on youtube.