Filling out my own taxes I pay $105 towards child support every week. Where are my W-2? Can I find it or how do I add it?

You don't report or enter Child Support on your tax return.   You get the W2 from your employer.  Or do you need to enter a W2 you have?

To add a  W2 just type w2 (small W)  in the search box at the top of your return and click on Jump To the W2

OR  To Add a W2 enter it under

Federal Taxes on the left side

Wages & Income  

Then Wages and Salaries- Click the Start or Update button

Child support is not normally shown on your W-2, and you do not add it to your W-2. If the child support is being taken out of your pay, it's possible that your employer would show it somewhere on your W-2. There is no box for child support on a W-2, but they could possibly put it in box 14, or in an unused space on the form. In any case, it's just for your information. It doesn't go on your tax return.