Step 1: Download
GIMP 2.8.4 or whatever version from the website.
Step 2: Download one of these grids:
One Two. ALTERNATELY, if you prefer a more compact grid,
I have one with 25x25 tiles.NOTE: You may still want a different grid size/shape/format. There are plenty like this on the web, I just made these in Flash for easy demonstration.
Step 3: Start up GIMP and go to File>Open. Make sure all three of your main dialogs are open like this.
ImageStep 4: Browse to where you saved the grid and open it in GIMP. You may have to go to View>Zoom>100% as GIMP tends to zoom out if an image is too large for your screen.
Step 5: Select the Bucket tool. This allows you to fill in spaces of the grid.
ImageStep 6: Now you should choose a color that'll represent filled or "unenterable" spaces on the grid - AKA walls the players can't just walk through, large bottomless gaps and so on. Some GMs use black but, since I tend to screw up stuff in my maps the first time I make them, I'd recommend a dark shade of red or similar.
ImageStep 7: Time to start blotting out the geography for your combat map! I hope you have it in your head already. Your players can fill in the details with your narration and a little imagination - the important part is it's functional. With the paint bucket tool still selected, click in between the black lines on the combat grid the fill in spaces with the right color. On the image here, it's supposed to represent a walled-in temple room, maybe for a boss fight or something. If you mess something up, just ctrl+Z to undo.
ImageStep 8: Since you're about to start messing around with more layers and don't want to lose any hard work, go to File > Save as and select "Gimp XCF" under the extensions. This saves a GIMP-exclusive XCF file that contains all the layer data and such instead of flattening it to a regular image.
ImageStep 9: Now to add the player pieces. You know, the tokens. Er - the sprites? You get what I'm saying. Now, of course, for games like MKW, I draw them all myself, but that may not be in your interest. A good, serviceable option is text: for example, let's say Durham and Anciano are facing down three Goblins in the temple room. What I'm going to do is use the Text tool (the big T), click anywhere on the grid and then type in some text to represent everyone. Durham, for example, might be Du, while the goblins might be Go1, Go2 and Go3.
ImageStep 10: Notice something about those text pieces there? That's right: they're off position. So, for example, let's assume we want to move Goblin 2 around the combat grid. What we'd do is click on his layer in the Layers palette
(Image), choose the Move tool (the 4 arrows)
(Image), select
Move the Active Layer in the Tool Options (this is very important)
(Image), and then drag that text layer where you want it.
(Image)NOTE: This is technically doable with the Text tool, but it's very good practice for working with a layered image when you want to move/manipulate things other than text.
Step 11: Position the rest of the player pieces where you want them on the map and you're done! If you want to move something in very small increments, just use the arrow keys on the keyboard with the layer selected. Save this image as XCF again so you can come back to it when you need to update the combat map.
ImageStep 12: For the very last step in GIMP, go to File>Save as... AGAIN the select
PNG as the image type. This creates an uploadable image file that you can easily share on the web. The reason I use PNG is because JPG is lossy and BMP is way too large. Some menus will pop up after you save as png, just click OK/yes/accept or whatever to all of them.
ImageStep 13: Go to imgur.com and upload an image by "Computer." Browse to the folder where you saved the PNG and select it then hit "Start Upload."
ImageStep 14: Once the image is loaded, copy the BBCode link as shown here. Paste it as-is in the forum and VIOLA! You have a combat map in the game!
ImageAs a note: when you want to update the map positions (perhaps for a new combat round after a lot of rolls), just open up the .xcf file in GIMP and work through steps 11 to 14 again. I realize this sounds complicated, but it's really quite easy/fast/simple when you get the hang of it. Hell, even my MKW battle maps take me 2-3 minutes tops to put together, it's mostly just the face sprites and other illustrations that take more time
Good luck, and if you have any other questions or spot any errors, feel free to ask/complain!