I reside in WI but worked both in WI and AL. Do I enter income from AL on my WI return or do I fill out returns for both states?

You file returns for both states. If you were only on a tempoirary assignment in AL then first complete a non-resident return for AL, paying AL income tax on your AL-wages. Once you've done that, then you complete the standard resident return for WI. You'll have to report all income to WI (including what you earned in AL), but you then take a credit for taxes paid to other jurisdictions (namely AL). The result is you don't get taxed twice on the AL income.