Read here before posting!!!

Now Before you go on asking about "How can I edit dsdoom assets" This thread should answer your questions.

Lets start with the basics
-Mapping
Now ,If you want to make your own doom or dsdoom maps there are multiple mapping programs available for you to use.

DoomBuilder

DoomBuilder being my favorite, its easy to use and makes good maps in a short period of time (Highly recommended *****)
Download
• Doom Builder 1.68 full installation

WadAuthor

This is one is the most basic doom editing program very straight forward but isn't all that practicle for large maps (not recommended **---)
Download

DeepSea

Now this is a more modern map editor and is probably second best to doombuilder Although its not free however the trial version should get the job done, infact it comes with quite a few prefabs for making quite doors, lifts, etc. (recomended ****-)
download

SlumpEd
This is another basic map editing program although it has a few more features then WadAuthor (worth trying out ***--)
Download

-Wad Editors (primary for sprites, sounds, etc)

Wintex

This wad editor is my favorite for creating doom & doom2 wads, Its easy to use and is a great way to make quite wads. Or transfer assets from your current project!And is small in size so you don't have to worry about storage space (***** Highly recommended)
Download

XWE

This program is a must have for all wadders, primarily because it can do everything wintex can do and more
you can even load Dehacked files in it Although it might feel bland at times (***** Highly recomended)
Download

Dehacked Editors
I only know of one, its called WhackEd2 its the best you could possibly get too! GET IT!!!

Now For Tutorials
You should be able to find whatever answer you want on

http://zdoom.org/wiki/Main_Page

If you seek video tutorials you can watch these
videos I have currently two tutorials one of Doombuilder and one of wintex
http://www.youtube.com/user/FANADICALCOWHEAD