Loading a jpg into a specific spot like an html page

Hi i have a photo gallery in wich i load external Jpg into an empty movie clip but i also want to load smaller thumbnails with small jpg into my buttons(externally) but i don’t wanna do it with a button action and an empty movie clip , i wanna do it almost like an html page would do it so as soon as i got to where the buttons are located the jpg will load into an hotspot (behind the invisible buttons) , basically i wanna be able to change the thumbnails images externally without going back into the fla.
It is very confusing but i am still a beginner so please be patient with me.
Thanks for your help