It's really easy, takes 10 mins.
Think of spokes as long thin bolts. Each one has a 'head' at the hub and a 'nut' (aka 'nipple') at the rim. And each attaches to the hub on one side or the other.
To move the rim at a given point to, say, the r/h side, just follow a spoke at that point on the rim down to where it joins the hub. If it joins it on the r/h side, tighten its nipple and loosen its neighbours - about 180 degrees turn at a time. Repeat as necessary.
A tip: if you get confused about which way is tightening, and which loosening, imagine that instead of using your spoke tool you were using a screwdriver on the top of the 'bolt'/spoke.