You will still file as married. Typically married filing jointly yields the best tax result. You will enter your husband's self-employed business in the "Wages & Income" section using the self-employment topic. This will generate a Schedule C for that income source. In the self-employment topic you can also enter his business expenses so that only his net income is taxed.
Here is a helpful link.
Be advised the social security and medicare taxes are split between the employer and employee but as a self-employed taxpayer the sole proprietor is both the employer and the employee so those taxes will be added to your return as self-employment taxes. TurboTax will automatically calculate those and add the proper forms for reporting using your entries in the self-employment topic.
Here is a link with more information on self-employment taxes.