Making my own mod?

Hi there. I want to make my own Mod. I use Lucas Pure3D Editor 4 to change the car graphics (colors, sizes).
First I exported and then imported the picture, but after importing it opened a window (after starting the game and selecting the car from the phone booth), that the pixel size is too large. I'm not sure it that wrote this because I didn't understand what it was writing.

My question is, how can I fix it, that the window don't writing it out, and that game running with the new graphival appearance?

(I'm sorry for the grammatical errors, I don't speak English so good.)

Thanks for reading.