Choosing a Layout and RAGE

I'm considering learning how to make layout because I would downright KILL for a Wii U/Splatoon 1/Puyo Puyo (Sega era ofc) themed layout. Literally EVERYTIME I try to apply a layout I think is cool there's ALWAYS, GUARANTEED, SOMETHING WRONG W IT. Example, there is missing images, my music or pfp is bugging out, my custom cursor is overlapped, specific strings of code don't work, Etc etc..

If anyone knows how to code pages or even has some tips or guides PLEASE help a Dude out

Seeya!