Guide on adding a new model, animation, and creature to HoMMV

Without extracting, just double-click to open the archive, and do the same with the game file. Copy using Ctrl+C and paste using Ctrl+V into the data folder. This way, the date and time on the file won't change.
The archive contains a folder with two files: the texture itself and its text-based xdb file. Copy only what you deleted to avoid replacements.