Swapping out an image with one's own?

So I don't use FF all that often but it occurred to me with all it can do there must be a way to swap out an image with one's own from another setup that I like.

I have a bunch of homemade textures and while I'm not very good with node based setups I'm getting more used to it using Poser 11 and 12 so I'm not a total duffus but I have found a couple of already made settings that come with FF 10 and all I want to do is replace the image of the sunflower and ladybug with my own to see what I can accomplish with it but when I do a search for image up pops an image node option, I drag that out and I see no way to add an image from there.

I would THINK that a drag and drop option would be a smart way to go with this but that didn't work either. So need some help understanding how to add one's own image to the work area to hook into these other nodes so I can play with my own images.

Thanks so much
Richard

Some filters use a spot in the settings tab. Click on the arrow.

Thanks so much! I appreciate your time in explaining all that to me.