How to do Flat Barbell Bench Press:
Lie down on a flat bench with your feet flat on the floor.
Take a medium grip on the bar using the smooth rings as a guide. Generally, a good rule-of-thumb is to place your middle finger on the rings.
Experiment with grip widths until you feel comfortable then remember where that grip is.
Take the bar off the rack and hold it out at arms-length.
Lower it slowly to the nipple line then press up in a slight backward arc so that the bar finishes approximately over your face.
You should inhale as you are lowering the bar and exhale as you are pressing up.