I created my game login page and index. but then what next how can I create my game and load it in the browser so it works like slither.io
Forums are for more specific questions, not how do I create a game.
There are too many possibilities on how any game can be made. Follow a tutorial, it’s not something people want to answer in the forums when there are tons of resources out there for this exact type of question.
Maybe the loading part is a question suitable but the context of the question is about creating a game like slither.io.
It took me little effort to type and get this.
https://www.google.com/search?q=create+game+like+slither.io+unity
After that choose one, follow along and do exactly what it says.
The purpose of this forum is to assist people who are ready to learn by doing, and who are unafraid to get their hands dirty learning how to code, particularly in the context of Unity3D.
This assumes you have at least written and studied some code and have run into some kind of issue.
If you haven’t even started yet, go check out some Youtube videos for whatever game design you have in mind. There are already many examples of the individual parts and concepts involved, as there is nothing truly new under the sun.
If you just want someone to do it for you, you need go to one of these places:
https://forum.unity.com/forums/commercial-job-offering.49/
https://forum.unity.com/forums/non-commercial-collaboration.17/
https://livehelp.unity.com/?keywords=&page=1&searchTypes=lessons