I am super new to this and i have seen alot of rom hacks that have edited the screen you see before a level starts and i was wondering how i would go about doing this.

been doing Photoshop stuff for years so i just need to know what files i need to replace and weather i need to dip into ASM hacking

It is an ASM hack for this. It is made by Skawo. You can find it in the ASM hacking section