Where do you put the oil in a 1980 Honda goldwing 1100 interstate?

The filler cap is on the right side, lower part of the engine. There is no dip stick. Its a window that you look in, in the same area. On the center stand, look in the window with a flash lite to see the level. If the engine has enough oil in it, then with the engine running, as you look in the window, have someone shut the engine down. You will see the oil level off to be able to see the level.