How do I fit new fan oven element, beko dvc 565 electric cooker?

I have the new element for my cooker , beko dvc 565 fan assist electric oven , the element has been replaced before, but it's been a long time ago and I got an electrical engineer who was in my local newspaper he wasn't the cheapest,LOL the fan is working but no heat coming from the main oven, so I would appreciate if someone could give me some more info on how to do it myself,please thanx