Cucumbers, tomatoes and chillis

Hi,

I am currently growing cucumbers, tomatoes and chillis in 2 mini plastic greenhouses.
Any suggestions as to where to positions these crops, in direct sunlight, shade etc?

Also, I have a friend with a plastic greenhouse who opens the door of it all day, so it doesn't heat up too much. Is this a good idea?
Cheers
Steve

Thanks for that.
Any idea if cucumbers like the sun or shade?
Cheers
Steve