I need to make a sprite. I was instructed to make one layer an editable layer and another layer that is a flattened bitmap layer. Any instructions on how to do this would be appreciated.
All pixel layers in Photoshop are "bitmap" layers. Simply don't use any of the vector or type tools and if you do, rasterize them afterwards. Or choose Flatten Layers from the
Layer Panel menu and you are left with 1 "bitmap" layer.
Adobe's use of the word "bitmap" in their application does not redefine what the word "bitmap" (see Pixel Storage at the link) actually means. Adobe's menu items are not the definition of a term in many instances.
In global terms, "bitmap" merely indicates a raster image or image where pixel data is stored as opposed to vector or other forms of image data.