Please break down the following $32$ bit instruction to show me how the format works. Use spaces to distinguish which parts are the opcode, register, and memory offset.

LDUR X$2,[$X$20,$ #$8]11111000010000001000001010000010$

STUR X$4,[$X$20,$ #$16]11111000000000010000001010000100$

Note that the equivalent answers are already there in the commands $($LDUR and STUR commands$).$ I want you to show me how the formatting works, and how it's determining the different destination registers & memory offset? The last part, how they determine what offset of memory is$,$ is the most important.

I believe the formatting starts with $11$ bits being the opcode, but the rest is confusing to me$.$