Rad air lock question?

[H8NSKPAUL]

Hi Guys, I hope you can help us?
We have had a new radiator made up and we fitted it this weekend, the thing is it now has an air lock somewhere, the car over heats even though it appears to circulate.
We had to remove the old rad to give to the place we had a new one made as they re-used the ends and it was used as a template to make the matrix the same. However the car was in my workshop for a further week being finished off and I had to start it up and move it outside on a daily basis. So the system had no water in it and the pump would have run for the minute or so it was running. Is there any bleed valves or specific re-fill method.
Any tips would be greatfully received.

Many thanks in advance.
Hans and Paul.