How to finish wood<br>Sand down the wood. Wood will have flaws like scratches and dents. Whether marks have come from the machines at the mills, or it has become scratched or gouged during handling, or from wear and tear.
Sanding the wood is the first step in wood finishing.
The context looks like steps from a tutorial and sanding was the first thing brought up so it must be the first step. I think it was difficult because the context never mentioned the word steps. 
( z0 thing :ARG4-of ( z1 step :ARG2 ( z2 finish :ARG1 ( z3 wood ) ) ) :domain ( z4 sand :ARG1 z3 ) :ord ( z5 ordinal-entity :value 1 ) )
(z0 / thing
    :ARG4-of (z1 / step-01
                 :ARG2 (z2 / finish-01
                           :ARG1 (z3 / wood)))
    :domain (z4 / sand
                :ARG1 z3)
    :ord (z5 / ordinal-entity
             :value 1))
Sanding the wood is the first step in wood finishing .
z4 :ARG1 z3
z0 :domain z4
z0 :ord z5
z5 :value 0
z0 :ARG4-of z1
z1 :ARG2 z2
z2 :ARG1 z3