...
After that, you can create a bigger block that includes the IES block and the light fixture, for instance.
I cannot see the effect of the light. Why my light doesn’t illuminate?
First of all, the scale of the scene is very important. Very big lights require very powerful lights and/or a very sensitive camera. The first thing you can try is going to the Properties panel with nothing selected to see the camera settings and lower down the exposure value (EV); this will increase the sensitivity of the camera. Also, a very big light (several square meters) will require many lumens to be visible unless you are using luxes or luminance units (which depend on the size of the emitter).
Also, there’s a big power difference between environment lights (for example, the Physical Sky) and spots, area lights, etc. You can turn off the environment to see what’s happening with your lights (set it to “None”).