You can open the .rte and a .rvt (revit project) in the same session, and use Manage>Transfer Project Standards to copy the ceiling types from the template file into your project.
@kevin_peter wrote:I have a celings type with rte file(template).
How can i use it?
Use it how? As the template for a new project? Adding the RTE to the Project Template Files, listed under File Locations in Options, is the easiest and most direct route. Otherwise, Browse for it when you start a new Project. You're going to be prompted to pick one (a template) at the onset.