Deductions & credits

Each year I find my self needing to come back to this community forum to understand how to do this. The clear, logical answers found here never seem to jive with the vague and convoluted explanation in TurboTax. If my wife makes more than I do, do I just need to put what she makes in my adjustment ADDITION? Or to I ALSO need to subtract MY OWN earnings via the Subtraction Adjustment?

The basic idea seems simple enough. Why can't it be explained in a straight forward manner? It's much like asking a simple Yes/No question to a politician and getting 3 minute, mind-numbing non-answer.