Need Guidance for Listening Room - Music-Acoustics Forum-Acoustic Fields Forum

Dear Sir, I have been listening to your Acoustic fields channel for quite a long time now. I am a complete newbie to this field. I do sculptures and carvings. My friend asked me to design Acoustic panels, and i also made some just like that from a decorative point of view, but that seemed to have created a difference. Not sure exactly if its on the positive side. ( i could send the pics if you want ).
Now another person have asked me with the same. Since i want to do it dedicatedly for this some, i wish to have you people’s guidance.
The dimensions of the room as follows 21 * 10 * 8 feet ( L * W * H ).
Kindly help me design this room, as i wish to learn this art from the beginning.
– Thanks in Advance.