1.in the run/search bar on your computers menu type %appdata%/.minecraft
2.open your bin folder
3.open the folder in your bin folder called minecraft.jar with a program such as 7zip or winrar (i recomend 7zip because its free)
4.create a folder on your desktop to store your textures and work on your texturepack
5.in the minecraft.jar folder opened drag across the folders named: achievement armor art enviorment font gui item misc mob terrain title pack.png pack.txt particles and terrain
6.once there in your folder open the textures you want to edit with a photo editing program that can create transparent textures such as photoshop
7.to test the texture pack simply drag the folder into your minecraft texturepack folder

to make a hd texturepack click on images then resize image
x2 for 32x32
x3 for 64x64
4x for 128x128
5x for 258x258
6x for 512x512

leave a diamond if you found this usefull