I am having 5.1 speakers and I would like to know what is the best setup that we can have in Onkyo HT R391 AVR with blu player for an outstanding performance.
My room size is like this H:13 ft, W:13 ft, L:18 ft.
That AVR does not include any auto setup or calibration function. You're going to have to set it up manually. I would refer to the manual, it's available online, for instructions on how to do this. You should really only need a tape measure to get the distance and the speaker specification to set the xover points. You can use the test tone to set the level of each speaker.
Unfortunately this model is a manual setup one so you have to some effort into it. There is no universal setup that I or anyone else can give you.