Sorry, I just may be not the best person to introduce you to map making
But I'll try better:
1. In your 'Darkest Hour\map\Map_1' folder you will find map definitions. Small part of it is easily readable (stored in csv files) but most of it is encoded inside binary files in a format read only by Europa Engine games (those tbl files).
2. Some inventive people at these forums reverse engineered this encoding (with some small help from Paradox AFAIK) and allowed those tbl files to be decoded and widely readable files to be extracted. The most interesting files are index.tbl and lightmap*.tbl and if I'm not mistaken, they contain, respectively, colorcoded ID map (one color = one province) and map that appears to the user (with province borders, names, etc.) - there are several files because there are a few zoom levels.
3. I gave you a link to one such program (Magellan). There's one probably better program, better suited for DH, i.e. Jamie's Map Utility (there's a long guide with links here:
http://forum.paradoxplaza.com/forum/showthread.php?366310-Noob-s-Guide-to-Map-Modifications).
4. The programs let you extract PNG files from these tbl binaries. When you have those PNGs, then my program comes in handy. You can import extracted PNGs, click on the map and edit properties of each province. Some are easy to edit anyway (energy production, name, etc.) some are less straightforward otherwise (icon positions). The program doesn't let you to do any heavy-weigh editing of the map itself (moving borders, changing visible descriptions).
5. When you make all edits - those in my program and those outside, in graphics editor, you can recompile the tbl files and get your edited map.
The caveat is that I never walked through the steps above because I don't do map editing. That's why I don't have any PNG files at this moment - I think I never had original DH files, I had files for an alternative modded map once, when I coded this app, but that was some time ago.
My program is only a small helper when compared to Jamie's utility for example and if you are really interested in map editing then:
1. Read the guide I linked to above:
http://forum.paradoxplaza.com/forum/showthread.php?366310-Noob-s-Guide-to-Map-Modifications
2. Ask in some thread concerned with map modding, this thread is especially formidable:
http://forum.paradoxplaza.com/forum...ject-for-Darkest-Hour-1000-s-of-New-Provinces
If you want only the PNG files, the E3 thread may give you some pointers or you can use the Jamie's app to extract then yourself.