If you have been around during the FNAF Modding era, you might already know how this works. However, if you are here to learn, you have come to the right place.
Ultimate Custom Night on Steam or Gamejolt
Texmod (There are some people who have been getting errors and problems with the version they are using so try using this version): https://mega.nz/#!nyhCCYQL!fzzV3D6EA7mi5jnOmHg_pKdiwudINdD1_MSW_OYI9bU
A photo editing program with transparency (paint.net, Paint 3D, etc)
Start by Opening Texmod.
Click the folder icon inside Target Application and browse for UCN.
Steam Directory: C:\Program Files (x86)\Steam\steamapps\common\Ultimate Custom Night
Gamejolt Directory (If using Client): C:\Users\(your name)\AppData\Local\game-jolt-client\User Data\Default\Games\UltimateCN-349545\default-364920\data
After browsing, go to "Logging Mode" and make sure you have these settings:
Afterwards, pick the output folder for the textures and click "Run"
You should see Red Text on the Top left corner that says:
"Press + and - to select a texture and Enter to save it. Press , to reload replacement textures. Hold * to filter drawn textures. Press / to reset filter mode."
Play the game for a bit to load whatever textures you want. Afterwards, press + or - to browse the textures you want to mod. Once you find a texture you want, press Enter to save it. It will appear in the folder that you chose.
Once you are done with the textures, quit the game and edit the textures to your liking. DO NOT Edit or Delete TexMod.log because that is required for Packaging which is explained afterwards.
Once done go to Package Build. Browse for the Definition File or in this case, "Texmod.log".
Afterwards, put your Creator Name and Comment if you want.
Click Build and type the name for the tpf file to create.
Now the mod is ready for testing and uploading.
To test or play mods you and others have made, we go to Package Mode. Next to "Package Name" click the folder and look for the tpf File. Once done click "Run".
If the edited textures have loaded, then you have done it and the mod is ready for uploading.
That's basically all for this tutorial. Hopefully it helped. This method also works with the other FNAF Games. If you have any problems or questions, I am happy to answer them. Happy Modding! :)