Submersing the knit into water evens out the stitches. All yarns are not necessarily clean; this is an opportunity to clean the yarn as well as block. I mostly knit with wool, but this method works with all fibres. Very little extra steam blocking is needed when dry.
The blocking board is styrofoam insulation board from a building supply store.
The wooden block is for smoothing out the knit as it is pinned to shape on the blocking board.
The bucket may contain a mild cleaning solution or none. Rinse well when appropriate.
Squeeze item to remove liquid, do NOT “Wring out” tightly. Roll in a towel to absorb more liquid. Some knitters will put the item in the washer on a delicate spin cycle, before pinning to shape.
Hopefully, the photos are self explanitary.