Blender green screen video overlay over a trackmotion

i am not sur i am at the right place. sorry for my complete noob… anyhow… i am stock… i have created A 2d video greenscreen of an FX explosion. so i remove the greenscreen all os good in composition. a save all this. like tutorial say as image. any how i get the video a get the sound.

i want to overlay this on an existing video footage of my girlfriend that when to jordan. i use camera trackin. all is good i get perfect motion… 0.14-0.24 pxl evertime i do it. . but every way i try to export the video and every way i try to incorporate the to together as a forgroud back groune i cannot get to see any resul of get to see any video. so i render everything blindly i just cannot get the explotion to follow the camera traction of original footage.

when i import the video as an image plane. i can only see what is going on after i render image. but i do not have any video or cannot she the wort. tho the camera in blender does the same motion as the original vide and the set image plane moves when i set active camera. nothing seem to happen. i’ve been at it for far too many hours. i just cannot seem to see any of the work like most online video. i have tried rendering all kind of coding. i cannot get a transparent video that i can just over lap or even imaging i don’t understand. annnddd i know deep inside its something very stupid. like a siggle action otlr the click of a button

after many attempt i manage to sync my motion tracking with my Fx . wasen’t easy but the Fx is soit on. it almost looks real. i had to redo it a few time. but in the end i got my answer . fir some reason i could not see my render image causing render animation to be blank . after many trial and error by changing setting one at a time i manage to do it.