You will need the following:
-GIMP, or a similar image editing software. Get GIMP for free here: http://download.cnet...4-10073935.html
-An image of your choice saved to your computer
-The gold required to make it
-The land required to build it
Forewarning:
Things aren't going to look exactly like the original image. Colors may have to be changed in certain areas to make up for the lack of color options.
Detail may or may not be lost depending on how large you're willing to build, what you build, and what colors you use.
Step 1 - Choose an image. I'll be using this loli girl wallpaper Zooty provided here:
Step 2 - Edit your image. Open the image with GIMP, then in the top menu go to Filters > Blur > Pixelize.
Next, set your Pixel Width. The smaller your pixel width, the more detailed (and larger) the art will be. Use your judgement. In this example I set my pixel width to 3.
Now you're going to want your image to be more 'pixel-like'. So adjust your brightness-contrast. High contrast, low brightness works best.
Step 3 - Changing the colors. At the top go to Image > Mode >Indexed...
Look for 'maximum number of colors' and set it to something realistic for your image to be made in 8bitmmo. Like 8.
Now go to Windows > Dockable Dialogs >Colormap. Here you will see the current colors being used in your image. If a color isn't available in 8bitMMO, change it to something else. I had to change the brownish color into roof-orange (shown), the lavender/violet color into red (not shown), and very light violet into grey (not shown).
After you have it how you want it, go to File > Export As and save it somewhere. Now reopen it, zoom in, and get to work!