I had extra leave days that I sold while in the military and the government taxed it 25% can I claim this on my taxes and how to do so

The amount the military paid you for your leave days is considered income.  You will receive a tax form for the amount you received separately from your W-2.  

You will add the amount you received to your income and then enter the amount of tax withheld.  If the amount you received raised your tax bracket, then you may owe more.  If it did not raise your tax bracket, you may get some of the 25% back.  TurboTax will do the calculations for you.

On a side note, DFAS normally only posts the W-2 for pay online, so you need to wait for this tax form for the leave payment.