Openframeworks is a set of tools to streamline writing software, so you will need to write software to work with the tools discussed here.
References to “addons” or code with the ofx prefix, means that is a set of classes and or libraries that can be used inside openframeworks.
The best place to start is at the beginning - https://openframeworks.cc/download/
There are comprehensive setup guides, and a lot of tutorials https://openframeworks.cc/learning/01_basics/how_to_add_addon_to_project/
Addons are not part of the core code, so they are community contributions that are not always maintained. It is up to you largely to try it and see if it works. The OfxWarpBlend addon is 2 years old and openframeworks has changed a fair bit since then. You can try your luck, or have a look through http://ofxaddons.com/categories and see if there is something else that has the functions you need.
If you are working outside of openframeworks with your project in general, these addons will not be so usefull as they are built around openframeworks unique types and structure. You may be able to adapt the addon yourself to the environment you are working in.