Question about compositing in blender

I have tracked a drone shot of an old water tower. I would like to composite a graphic on the side of the water tower.
What is a basic method or tutorial I might be able to reference to get me started.
Better in cycles or eevee?
any help or push in the right direction would be very much appreciated.

A bit of a late reply, so I hope this will still help you :wink:

If you have a proper 3D track, you can start adding 3D models to your scene to see if the tracking ‘sticks’ the models in their place.
If they slightly move from their location during playback, the 3D track isn’t totally correct, or the placement in Z space is a bit off in most cases.

When you have this all worked out, it’s as ‘easy’ as placing the geometry for the graphic in 3D space, add the textures and render out the sequence.
Now in compositing, add the rendered sequence on top of the water tower footage. Maybe adjust some black and white levels to get both layers as close as possible, and do some color correction on the final comp if necessary.

One final note on tracking, as 3D camera’'s don’t have lens distorting (well… only in post) you will have to compensate for that before you start tracking the shot. Or it will not work properly.
Never used tracking in Blender, so I don’t know if you can compensate for e.g. barrel distortion.
You’ll end up with a new sequence that is undistorted, and will match your 3D camera much better after you track the undistorted footage.

there’s lots of info to be found on the web and YT on this too.

Good luck with the project, and show the end result here if you can.