Hello again,
This folder is the biggest part of your texture pack, both of importance, and of size. The higher the resolution you desire, the bigger the file, thus, the bigger this folder will be. To make a block, simply launch/load the desired image program, and select "New". Resolution depends on how many pixels wide/long the block is. 16x16 resolution is the vanilla texture/size. 32x32 is twice as detailed as 16x. 64x64 is 4 times as detailed as 16x. Simply make an image that is as wide and long as you want the resolution to be. Example- Minecrafter1 wants to make a 32x texture pack, so he/she would make the image 32x32 pixels. All you have to do once you are done making your texture, simply export it to your desktop and drop it into this folder.
