" I am sorry bro but I am confused how to upload html5 file here"
No worries, it's the weekend, I'll find time to play it, but for other people here are the steps you need...
Step 1: Export File from C2 as a HTML file.
Step 2: Zip that file.
Step 3: Upload the File to Itch.io
Step 4: Check playable in browser.