Used premier for taxes and the total tax liability is zero. Zero ordinary income. Sch C loss rest of the income is retirement, SSA, and capital gains. How do I check?

You can see all your forms by clicking Forms on the upper right, then selecting the forms you want and clicking on them on the left.  Look at the 1040 to see how taxable income is calculated, and look at the worksheets for capital gains to see how that tax is calculated.  The standard deductiion is quite high this year and the level of income for zero capital gains is also high.