Java Moss should work. I now have it on every piece of wood in all 7 tanks, and it originally came with one or more of the original pieces of wood. It can be slow to establish, but once it is settled it will spread to the point of having to be pulled off to thin it from time to time. It also takes a while to acclimate to different conditions, such as changes in light, water parameters.
Sometimes you can get a piece "free" when buying wood, plants or fish; just wedge it onto the wood somewhere, or use black cotton thread. Once placed on the wood, it will begin to root and spread. But as I said, it can be very slow at first.
It does best in less light, by which I mean under the shade of overhanging plants, or floating plants. Out in the open, I find brush algae will appear with it on wood. Depending upon your tank's biology, a liquid comprehensive fertilizer once a week may be needed for nutrients.