Unless you have a dedicated space that is regularly and exclusively used for business, you can't deduct a home office. Having a computer that you do work on isn't the same thing. Even if you had a desk, the square footage of the area would probably be only be about 4 square feet. That's not to say you couldn't take an office with only 4 square feet but it would not provide you with much of a deduction.
You would need to get a tape measure and actually measure the size of the office. Then, you would need to know the entire square footage of your home. If your home is 800 square feet and your office is four square feet, you could deduct .5%of related expenses.