These files are for resetting your character to "zero" -- level 1, and no experience gained toward any skill levels or toward the next character level.
You may want to do this for various reasons, such as to replay your character differently without completely restarting your game and losing all game / plot progress.
Note that the game does not normally support character levels going backward, so there may be unintended consequences and quest-breaking, but this is in general unlikely. Nevertheless, before you reset your character, make a backup save game in case you need to roll back.
You will need to know how to run batch files with the Skyrim console.
Copy the file 1.txt into the Skyrim executable directory. This is the same directory in which the Data folder is located. Do not put it inside the Data folder like you would a regular mod.
Copy the files gqZero.esp, gqZero.bsl, gqZero.bsa into the Data folder and make sure gqZero.esp is enabled.
Go to an interior cell, preferably one where you are alone. Remove all gear. Use the console command dispelallspells to clear any temporary enchantments.
In this step, we set the character's level to 1, reset skills to 15 and clear all perks.
Run the batch file using console command bat 1.
Since all skills are now 100, change them all to Legendary skills. This will clear all perks from their perk tree, reset the skill to 15, and set accumulated skill XP to 0 for each skill.
Get the activator item for further resetting your character.
Use the console command help "[Set" 4
Find the BaseID of the item [Set stats back to zero] and use console command player.additem <id> 1 to add it to inventory.
Click on it in inventory, then close your inventory. The script will run and the item will unequip itself.
Now check your character's stats. No skills should be legendary. Health, Magicka, and Stamina should be 100. Carry Weight should be 300. The number of free perks should be 0.
You are now ready to add racial adjustments. Use the player.setav command to set skills to correct racial starting values.
If you want to change your race and appearance, you can use the console command showracemenu.
A good batch file generator for editing your character can be found at http://vitaln.com/ehalos/skyrim/