Hi Steve, Flow works by remapping things from a base surface (or base curve for curve-to-curve flow) to a target surface.
Right now you have the text that you want to deform but no base plane under it - so the first thing you want to do is to create a base plane right under your text. The easiest tool to do that is to use Draw solid > Plane.
So make a plane that's positioned under your text like so:
Note that if you want to boolean the text you should probably make the base plane pushed slightly in so the text sticks a little bit out the back of it instead of trying to make it rest exactly on the end of the text. That will also make the end result sunk down a bit into the target surface which is better for booleans - it's harder for the booleans to process stuff that barely skims along each other. It's better when the objects punch through each other at least a little bit instead of just skim.
Now select just the text and not the base plane, and then run the Transform > Deform > Flow command.
The prompt will say "Select base curve or surface" - now select the base plane.
Now the tricky part - there are some different modes to flow and the default mode works kind of more like applying a texture that follows the UV space of the target - you have a revolved surface as the target and if you use that mode it will make your object kind of circle around to basically follow the way the control points of that revolved surface are arranged. But in your case here I think you want to apply the text more like you are beaming a decal on to the object, is that correct?
So for that kind of "decal apply" type operation you need to turn on the "Projective" option for Flow - that's a checkbox that will be shown right at this pick target stage of the command up here:
So turn on that projective mode checkbox and then pick your target object and it will make this result:
For the default non-projective mode it would work more like this:
So note there how with non-projective mode the radial structure of the target surface plays a big role in the result.
With non-projective mode you don't have to set the objects up in front of the other surface, it only matters how they relate to the base plane and then it takes that relation and places it in the same spot in UV space in the target surface.
With projective mode on the other hand, you do want to position the objects in front of the place you want to beam them on to.
Hope this helps!
- Michael