I have a elegoo mega 2560 with 3.5 in tft lcd display . I am confused on what belongs in the set up function to display my image .
Ok! So have you tried making any code for that? If so post it using </> tags.
can you also post information on the screen you are using? BTW I recommend googling
“Displaying a BMP image on a TFT screen with an Arduino”
but anyway here