Would like to correct my business expenses. I've paid for turbo-tax self employed, Havent filed completely and cant find a way to change buisness deductions

If you have not filed, click on the "Business" tab at the top then go to the first item in the list "Business Income and Expenses" click "Update" button and then click "edit" for the business that you want to correct, then scroll down to "Business Expenses" on this screen and select "visit all" or one of the other categories to edit.  Once you are in this screen you can change the amounts.

If there is no business tab, select the "Federal Tab", then the "Wages and Income" sub-tab, then the "Self-employed" section. You can open your Schedule C from here and manage the expenses from within it. 

Easier way to get to this section is to click the "Search" tab in the upper right and search for "Schedule C", then click "Jump to Schedule C".