Tempering or "drawing" the steel involves heating it to around 250°C for an hour or two. The steel takes on a yellowish hue. When the tempering is done the blade will be hard yet flexible and fairly easy to sharpen.
For my heat source I used a counter-top oven that I setup outside of my garage. (It was going to be a hot one today and having the big oven in the house on for several hours at near full heat didn't sound appealing.) I placed the over thermometer inside and set the blade on a block of steel.
I heated up the oven to about 250°C (475°F) for two hours, then let it cool. Once cooled to about 25°C, I repeated this cycle. Crucible recommends 2 soaks of 2 hours at 204 to 425°C. This temperature impacts the overall hardness. The aim is to get the steel hardness between 59 and 62 Rockwell C.
Different types of steels have different recommended tempering schemes.