If i lost about 6000 in stocks how much can i claim as a business loss and where on my return does it go?

Unless you are a Trader in Securities who has make the Mark-to-Market election (most taxpayers have not made such election), then your $6,000 loss may be used to offset any capital gains.  After offsetting capital gains, the remainder of the loss can be used to offset $3,000 of ordinary income.  If you file Married Filing Separately, your offset against ordinary income is limited to $1,500.

Any remaining un-used loss rolls over to the next tax year.  

To claim your loss, in TurboTax online, enter your information in Investment and Savings, which is under Wages & Income.   If you are using TurboTax desktop/download, the process is similar except you will begin the process of entering your information in the section Investment Income which is under Personal Income.

@svengreene

if you are a trader with the mark to market election that gets reported on from 4797 part Ii

you enter through the schedule c disposition report for non-depreciable assets.