I am really sorry and I hurt to say it, but you will need to know about 2 to 3 weeks of Photoshop or gimp experience in order to fully understand what I'm saying at the bottom.

 

Materials and programs that you will need:

A online image editor

          The best in my opinion are Gimp or Photoshop;  also you will need to have a brain that is smarter then a trained monkey...

NOW here's what you have to do, lets start with the basic stuff first:

1. Download the default texture pack off the site and save it on your PC.

2. Open the online image editor that you are using... I have tried and used all of these online image editors...

3. Now that the image editor is open....open the textures.png....

4. There are 2 ways that you can edit the textures.png that is either by making your own textures OR by changing each pixel...

5. Here is how I do it; I make the texture and then re-size it to 32x32, then

 

If you want to learn how to create your own textures then just look to the online Photoshop, it is the best program to create your own textures... I promise to you, if you have comments below or questions I will reply. I hope that I have helped