I'm trying to make this part a sheet metal but i can't select the curved surface between the two bends. I need to flatten this part so I can laser cut it. Also I need to know how to add holes to to the curved surface?
You need to make sure all bends are tangent in a sheet metal part. Your spline in the sketch is not tangent. I assume the bend in the middle is meant to be symmetric. If this is the case, see attached model for a different way of modelling this bend. Convert to sheet metal - choose a flat plane as a "ground" or stationary plane, and select the auto detect bends button. Suppress/unsuppress the flat part feature to get your flat part.
AttachmentsPart1.SLDPRT, 87.5 KB