All 8 screws are the same. All 22 nuts are the same. 4 standoffs are slightly shorter than the other 4. The short ones go to the left to the relay module.

To start place 1 screw through one of the holes of the back plate.

Fasten it with a nut.

Followed by a standoff. For the 4 left holes use the short ones. For the 4 right holes use the longer ones.

Finally place a nut to secure everything in place.

Repeat for all 8 holes.