How to I invite other kids to my sons birthday party

My sons birthday is coming up and he wants his friends to come. I don’t plan shit, I’m awful at it. Do I send invitations at school with him? When I was a kid that’s what was done.

Time, place, and your invited.

I know non of the parents at all.

I was thinking of just going to an indoor playground or maybe a park.

I’ve never done this before, he will be 6 and is in kindergarten. He hasn’t had friends until he started going to school and I’m happy he’s got lots now but I’m kinda shy and don’t know how to go about this. What if I send invitations and nobody comes?