How can I replace the lower oven door on Cannon Chichester 10675G?

The lower oven door on my cooker shattered, I have ordered and received a new door.

I have taken the old door off, by taking off the top bracket, and lifting it off, but how do I fit the new door? Do I have to take the side panel off the oven to access the back of the screws - there must have been a washer behind them when I removed them as I am unable to screw them back in.