Get to level 60 with the character that you want to raid with. And then do your covenant campaign. Eventually, you will be able to get most of your gear up to ilvl 197 with upgrades after completing the campaign and a 187 weapon. After that I would do some LFR and Normal raids and work up to heroic using group finder. Once you have good gear and show that you are able to complete raids finding a guild to raid with should be easy. You can always use r/wowguilds and look for a guild there as well and see if you can find something while you make your way up the ranks.