Severe pain lower lumbar. Prescribed Acetaminophen/Codeine 300mg/30mg every 6 hrs; was told could take Aleve (naproxen) also, but unclear how many times per day?

2 twice a day. 2 twice a day is a reasonable/ recommeded dose. Conditions such as high blood pressure and kidney disease can alter the recommended dose of alleve. The med you are on is primarily a pain killer. You did not say what the cause of your pain is. That may also alter the medication dose and choice.