Most flowers that are considered annuals are self-pollinating. Each self-pollinating flower has a stamen to produce pollen, a stigma to collect pollen, and a pistil leading to the ovule. Identify these structures in the flower. This will allow you to collect and move pollen to and from the correct structures.  The stamina (or stamens) look like little antennae that carry pollen. The pistil is usually in the center of the flower, and the stigma is on top of the pistil. The ovule can be found at the base of the pistil. Some self-pollinating flowers, such as lilies and roses, are also capable of cross-pollination. Pollen reaches the ovule by travelling down the pistil. The stop of the pistil, or stigma, is designed to collect pollen and move it down to the ovule. Use your brush to transfer pollen onto the stigma.

Summary:
Identify organs located on the flowers for self-pollinating plants. Transfer the pollen to the ovule.