Because of the chemical makeup of fabric softener and laundry detergent, you should not use them at the same time. It reduces the effectiveness of both of the solutions.
Fabric softener should be poured into a separate compartment from the laundry detergent, and the two should be released at different times to avoid any chemical interaction. Fabric softener is typically released first to allow the clothes to soften and be rinsed, and then the laundry detergent will help ensure that all of the softener is rinsed out of the clothes before they go in the dryer. To soften clothes without a washer that has a dispenser for fabric softener, use dryer sheets or a laundry ball in the dryer to help clothes come out feeling soft and fresh.