The tax last year would be found on line 61 or form 1040. The amount of a refund would be found on line 76a, and the tax due with your return line 78.
To evaluate the differences between this years return and last years returns, I would compare the following lines in your return:
Line 37 Adjusted Gross Income
Line 40 Itemized or Standard Deduction
Line 44 Tax and line 46 if applicable.
Line 55 Total credits
Line 57-62 if applicable.
Line 61 Total Taxes
Line 64 Federal Withholding
Line 74 Total Payments.
This lines will show you the most important differences between this year and last year. For example, if line 40 is lower you could be missing some deductions this year.
