The first step in steelheading with a float is to adjust for proper depth. Your goal is to place your bait or lure about one foot above the bottom. If your float continually drags under or tips downstream as it drifts through the run you a dragging bottom. Shorten the distance between float and lure until you can make the drift without touching bottom.
Your float should drift at the same speed as the current. When your float is upstream from you it should sit straight up and down in the water. As your float passes in front of you begin free spooling line while gently thumbing the spool to maintain just enough tension to tilt the top of the float slightly back upstream.
Ninety-nine percent of the time steelhead will hold on or very near the bottom. When that is the case you want your gear to be within a few inches or the rocks. On occasion steelies will stack in deep runs and will stratify well above the bottom. It may take some trial and error to find the depth they prefer, but when you do a float will let you put your offering right in front of their noses.