I was watching a tutorial about making an airplane. Here's the link.
He made some bezier curves that outlined the craft's fuselage and used bsurface add-on to fill the rest of the surface. The tutorial was in a blender version less than 2.8. He first selected the bezier curves, then selected a plane(I don't know what it is for. He just created it just before doing these things), toggled 'keep strokes' and clicked 'add surface'.
But when I tried the same thing, I couldn't find the same menu like the one in the tutorial, which is on the left side. I found something similar when I clicked 'n' and went to 'edit' tab, but the 'add surface' button didn't work with an error below. I also found that I could select objects with the spuit-like icon just above the red thing, but clicking 'add surface' with an object selected by that tool also showed an error. I guess it is saying there's no vertices to work with, but it doesn't make sense. The tutorial guy had no problem.
I looked for some other tutorials that delt with BSurface add-on in blender 2.8+, but they all used the annotation pen instead of the bezier curve. I think I don't know how to use the tool correctly, but couldn't find the way anywhere. Please tell me what I'm doing wrong and how to fix it.