Hello
Let's start off by finding if your country is in the legal list.



I found this on the website https://slotegrator.pro/gambling_blog/where-online-gambling-is-legal.html

Now let's think about what you would need.

1. Make a team
    Developers
    HR
    Management team etc ..
2. Plan!!!
Look for funding , make plans , check the schedule and start thinking for the future
3. Finalize the design of your website and look for reviews
4. Get a test start
5. Get involved with people on the forum and maybe start a campaign
6. Viola!! After so much hardwork you have your own gambling website.
7. Make sure to periodically involve yourself in campaigns because these are the ones which would get traffic towards your site.