after that, open Adobe Photoshop... then, open those files, you will see that those files are a Loading Screen but separate into 4 files that is BL(Bottom Left) of the Loading Screen, BR(Bottom Right) of loading screen, TL(Top Left), and TR(Top Right)...
Then, separate your own Loading Screen same as the monolith map do(into TL,TR,BL,BR), save your work(remember, save it into .TGA format)
Open your map, import your loading screen(TR,TL,BR,BL), you will see the path will be like this :
war3mapimported/LoadingScreenBR.tga war3mapimported/LoadingScreenBL.tga and so on...
change it into :
LoadingScreenBR.tga LoadingScreenBL.tga and so on...(delete the war3mapimported/)