Please find an attached file. I've assumed you'd like to randomise the offset of each row so to do this you can try the following:
- Create a transform operator and wire it to the Generator's Left input.
- Right click on the Transform operator and export Left Padding
- Attach a Random number node to the exported parameter and change the mode to Generate on Array Y Row
- This random value generated by this node will now create random offsets for each row.
If you need to enlarge the area to get rid of missing boards around the perimeter you can use the Generator > Clipping Area > Expand property.
I hope that helps,