Once you have your guild set up you need to get people into your guild. To do that you can use your friend list and invite people directly from it or you can invite people by typing in their epic name in the box shown in the image below.
You can also invite people from the recent players’ list you can see in that same image. Just right click and invite them to the guild that way. The recent players are those players that have been in your vicinity. What’s also useful about those lists is that you can see what platform the player is using to play the game. So if you only want people that play on PlayStation in your guild you can do that.