How do I bleed air out of my fuel line?

I have a Danesmoor 15/19 Oil Boiler. Could you please tell me how I bleed air out of my fuel line. I remember from the
book of instructions which came with the boiler, this was just a matter of opening a small bolt with a hex key. Then letting the air out, and closing it up when the fuel started to flow again. This involved it making a hissing sound, which stopped when the fuel line was clear of air.

I know it's a simple job really, I am just checking as I can't find my manuel at the moment.
Many Thanks