Fortunately, exporting the file is simple. Select everything you want to export, and then run the “export” command. Choose to export your file as an OBJ or STL.
The only difference I know of between these file types is that OBJ files can contain texture information while STL files are strictly for geometry. If you intend to order a full color sandstone print from Shapeways, for example, (see below) you would need to send texture information along with the geometry so you’d want to use OBJ format.
These are the settings I typically use for exporting meshes: