Little round knobs under the ark of the covenant
Since I'm not the author I won't be able to provide instructions, however it is quite easy for me to identify the pieces you are asking about.
&quot;Little round knobs&quot; are Brick, Round 2 x 2 Sphere with Stud / Robot Body (20953)

Bars are attached with the help of Plate, Modified 1 x 1 with Light Attachment - Thick Ring (4081b)

That's how it would look in the assembly: