Do you mean that you are self-employed? You are posting your question from online Free Edition which will not support preparing a Schedule C for business expenses. If you need to enter business expenses you will have to upgrade to online Premium or use any version of the CD/download.
You have self-employment income for which you will pay self-employment tax for Social Security and Medicare. You will need to use online Premium software or any version of the CD/download so that you can prepare a Schedule C for your business expenses.
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It depends. If you are referring to an office in the home and it is for your self employed business activity you can use the steps below.
You can choose to use the simplified method for your home office deduction. Count only the square feet used exclusively for business if you do not have another office location for your self employed business. There can be no personal use of the same space, regular and exclusive are the key components to qualify.
For more details about the home office deduction you can view IRS Publication 587. TurboTax will walk you through the deduction.