Collage Problems- Pictures

I'm having some difficulty with finding the right pictures for my collage. Like, I have an idea what I want to do, but I'm not sure if the picture I have are right for it. I don't know whether this means I should change the topic of my collage to suit the pictures or just try to hunt for more pictures. I may even have to get my parents to post some family pictures on facebook if it's not successful. I'm using the Glogger for the collage only because I used it before and know how to make projects look aesthetically pleasing on the website.