I am assumining it has a flat bottom airfoil. If that is the case lay it flat on a table andweigh it down flat or pin it to your work table. Use a heat gun on the top side. After it cools down check it out. If not to your satisfaction you will have to prop up the low edge and reheat the top agin. After you are done check the flat side for wrinkles or excessive stretching, if needed use the heat iron to even it out.

If it has a symetrical airfoil you would have to put it in some sort of a jig to even it outand do what I described above.

I hope this helps

Rafeek