Now we will add the Splash Image to the Dungeon Tile floor and just tweak it a little bit so it looks like it belongs there!
Ok now we'll need the image you created in Part 1 and the floor tile you created in Part 2; open both in Gimp (see The Tools below) and Configure your Grid to 0.178 INCHES again, then Show Grid.
1) Open/Select the splash image; then use the Magic Wand tool to select the main graphic. Here you can "Bucket Fill" a different color if you like, I'll make it red:
2) Copy [CTRL-C] this image and go/open your tile now; again be sure the Grid is configured correctly and Show Grid, and Snap to Grid are selected. Important! - Create New Layer!! Then on new layer Paste [CTRL-V] your image; you can rotate/move/re-size it to fit exactly how you like:
3) Once you've got the image at the size/position you want be sure to copy it [CTRL-C] before you anchor it to that layer. Once it's anchored you can then create a new layer and paste the image again; then using the Layer>Transform>Flip* tools create a mirror image on the other side of the floor:
4) Now let's make these look like they belong on a dungeon floor. To make this easier I'll 'merge' the two image layers into a single layer. Now on that 'image' layer I will change the Opacity to about 75%; and then using the Erase tool I will start subtracting from the images, especially in the cracks on the floor (the grid will help tremendously here):
5) The result should look something like this, then using the Erase tool again select a different 'brush', I prefer the "grass" brush and try this with different sizes and different (eraser) opacity to create a faded look:
6) Finally just make sure that your 'shadow' layer created in Part 2 is on Top and above the new image layer; then Export and enjoy your tile.
If I went too fast or too slow, or you have questions or suggestions please comment!
The Tools (all free/open-source):
Pyromancers Dungeon Painter
Again, I realize there are probably better ways to achieve the same or better results but I thought this might help some people - that said, if you do have a better technique, please let me know in the comments haha!