EDIT: Until I find the time to update this a bit, after checking this go see Thuztor's Mapping Guide! It explains this process in a bit more organized way 
Hi guys! Here's a little tutorial on how to draw "handmade" maps for the PZ mapping tools.
So, let's start!
1. Software
You need somekind of a photo editing software. Paint will do, but I would recommend something with a bit more options. You could go with Photoshop or similar, but I like to use Gimp as it's free and has many similarities with Photoshop, but it's a bit more simple. Also as we're only editing a few colors we won't be needing anything too fancy.
2. Maps
There are two maps we will be drawing. The "main map", which has roads, streets and lighter grass areas. Then we have the more intricate vegetation map. We will start by drawing the "main map". The image has to be sized by the amount of cells you want to have on your map. one cell is 300x300pixels which means that if you want to have a 3x3 cell map the image has to be 900x900 pixels. (I'm not sure which way the pixels have to be if you'd want a 3x5 map for example, but it is either 900x1500 or 1500x900 I'll update when I get the info...)
3. Drawing the "main map"
When drawing a map 1 pixel = 1 tile
Ok as said, we'll start by drawing the "main map". We have 6 colors to use in doing the map as follows:
The numbers after the description are the color codes in RGB. You'll have to use the exact colors or you'll get an error from WorldEd.
Green: Regular grassy terrain areas. This is what most of your main map is comprised of. 90,100,35
Dark Grey: Streets. Pretty self-explanatory. Most streets in game (and in the mapzoid created maps) are dividable by three so, 3 for alleys, 6 for roads and 12 or larger for highways, but this is totally up to you. 100,100,100
Light brownish yellowy type color: Yellow grass or dry/burnt grass. Grass objects placed on this will also have the yellowish color. 145,135,60
Light Grey: Walkways and such. nothing much more about it. 165,160,140
Beige: Sand. For dry prettiness. 210,200,160
Reddish brown: Mud. For a little more wet prettiness. 140,70,15
EnigmaGrey: Moderator. Be afraid. Be very afraid. There's too much backlight to draw this on a computer.
Here's an incomplete map I've drawn using most of those colors.
After finishing the your blueprint for your home town save/export the file as whateveryouwant.png
The file format is essential here. Use .PNG format as I don't think WorldEd accepts any other file types.
4. Drawing the vegetation map
We'll start drawing the _veg map over your existing main map. This is where it comes handy to have a little more than paint in your disposal as you'll be able to create layers and add those on top of the main map. There's another six colors that will define the vegetation. (If you're using paint or a program that overwrites the .png file, save this after a different name for now.)
This time we'll start with the last color, which as you can see is black (RGB: 0,0,0). The black color defines areas which have no vegetation at all, just the tiles you set in the main map.
Here's an example of what I do when beginning to draw the _veg map:
First, I black out all of the roads, and city areas where I want no grass or trees to grow. I set this at the top most layer.
Then the light green: Grass. This is the thick high grass that is in game, which hides them nasty crawlers. I usually just cover the rest of the map with this color and put it in the bottom layer. 0,255,0
Here's a sample:
After this I layer the rest of the colors ordering from top to bottom: Bright red, darker red, darkest red, dark green.
Bright red: Dense forest. This is what most of the surroundings of Muldraugh is comprised of. 255,0,0
Darker red: Forest. You can sort of walk in there, but not that much. It's still a forest. 127,0,0
Darkest red: Woods. You can walk around and see past some trees. 64,0,0
Dark Green: Grass and trees. Same as above but with some stray trees in the mix. 0,128,0
Here's the map with forests and woods added:
After that you're ready to go or you can add some small details on a top most layer:
After you're done with the detailing, save/export the file with the same exact name as the main map but with the end _veg
So in this case whateveryouwant_veg.png
DO NOT DELETE OR OVERWRITE THE MAIN MAP!!
Again, use only png format.
5. Adding the maps to WorldEd
Now that you have the two files, whateveryouwant.png and whateveryouwant_veg.png, make sure they are in the same folder. Then open WorldEd and from the top left click File, New... Then input the cell amount that responds with your map. Remember 1 cell = 300x300pixels.
You'll open up to this:
After that, on the left side of the screen click the maps tab and search for your whatever.pngs.
Then drag and release whateveryouwant.png on top of tha cells so that it matches the edges.
After you have the map on your screen, to convert the files to .tmx format (for editing in WorldEd and TileZed) click File, BMP to TMX, All cells, then choose the folder you want to use for the project and click OK.
After this again on the right side find the folder you just chose and drag the .tmx files to the corresponding cells:
6. Start editing!
Here are the .png Files I used in making this tutorial:
http://i767.photobucket.com/albums/xx319/elmosyrjalainen/MyfirstPNG_zpsb42a622f.png
http://i767.photobucket.com/albums/xx319/elmosyrjalainen/MyfirstPNG_veg_zps7f4b8629.png
Feel free to use them in your learning! If you use them as a part of your mods or something else please add proper credit. 
Sorry if I forgot something or left something out. This went on a bit longer than I expected and I'm a bit tired. (It's about 4am here now and I have to wake up in 3 hours) 
