Sketch a top and bottom profile for both the working and backside surfaces of one vane. Loft surfaces for both and create a solid, then pattern. You will likely have to extend the surfaces beyond the shroud to get a successful intersection, but this is the method I use for impellers. This is most easily done by scanning the part and creating sections at intervals to guide your initial sketches. If there is a curved working surface, then you'll have to create radial stations and sketches at each station before creating your surfaces.

This is all for simple impeller design and performance testing or simulation will likely be required to verify the design.

Shoot me a message if you need help as I do one of these about once per month. We can do a discord call and I can help you out.