Modeling aluminum plate heating

Hi.

I am lost and need some help.

I need to modeling the following case: The heating suffer by an aluminum plate that it is illuminated by a lamp formed by a matrix of 7x7 leds with a total power of 49 watts. The distance between the lamp and the plate is 20 cm.

How can I do it?

What physics are involved?

Do I need to model all leds or only assume that I have one led with the total power?

What about the boundary conditions?

Please, help me!!

Thank you