Can't figure out how to get a convex surface around a circle

I think you can see what I’m trying to do here. Can anyone help me out with how to make it actually work? I’ve tried follow me and I keep getting gaps.

I think your issue is your shape isn’t starting at a perpendicular spot. I see your shape is a little off from the green axis.

Thanks, the start looking to be a little off the green axis is what happens when I use the follow me tool. Your reply helped though and I got it worked out.