I dont think I have, Sorry to act dumb but how do i go about doing this? as I said im new to modding and Im an artist, code confused me haha @Reacon

I am currently creating a car mod for GTA V and am having major trouble with getting custom liveries into the game. I have got my car into the game and got the customisable car paint and custom wheels working in los santos customs but under the liveries tab I cannot get my livery to show up. I am using a sheava as a template and am modifying the files accordingly. I have replaced the embedded texture that the sheava has for the liveries and the colour of the car is changing but the texture isnt appearing. I was wondering if anyone on here knew how to do this as ive put hours into trying to figure it out and can't do it. This is my first ever mod and im a student.