W4 section "Enter Additional Amount, if any, you want withheld from each paycheck". Does this mean I am withholding this amount from taxes or from my paycheck for taxes?

A W-4 is given to your employer to have a certain amount of taxes withheld from your pay each pay period. It has nothing to do with you tax return except that withholding too much from your pay may increase your refund and holding too little from your pay increases the chance that you will owe taxes when you file your return.