How to register 2 CT datasets

Operating system:windows 10
Slicer version: 4.11.0
Expected behavior:
Actual behavior:
I want to register pre operative CBCT data over the post operative data and make few linear measurements on the 2 D slices and 3D reconstructions. How should i proceed. A video tutorial will be really helpful.

There’s a lot of information here: https://www.slicer.org/wiki/Documentation/4.10/FAQ/Registration