(Updated @Classics URL for how to make a critical edition.)
The NTVMR is useful tool for researching Greek New Testament manuscripts (and manuscripts in other languages as well). The platform can, however, seem daunting at first sight. Over at the Digital Orientalist, I have written a short overview of the NTVMR and given brief explanations of the its main features. It can be read here: https://digitalorientalist.com/2021/04/02/introduction-to-the-ntvmr/
You can also find helpful information about how to use the NTVMR under: https://ntvmr.uni-muenster.de/help
For those of you who are already familiar with the NTVMR and want to collate manuscripts and make your own critical edition, there is a step-by-step guide, now published in @Classics, which can be accessed here: https://classics-at.chs.harvard.edu/classics18-paulson/
This guide will show you how to view the differences between any manuscripts of your choosing (provided you or someone else has already transcribed them) on the NTVMR.
Image of Unedited Realtime Collation tool in the NTVMR
The NTVMR is not just a space to view images, but offers a customizable environment to build your own text-critical project. I hope you give it a try! Feedback is welcome.