[header] How to build pectoral muscles [title] Do bench presses. [step] To do bench presses, you will need a barbell and a bench. Lie back and grasp the bar with your hands shoulder-distance apart. 
Lower the bar all the way down to your chest and then slowly press it straight up until your arms are fully extended. Start with 3 sets of 10 reps and increase the number of reps and the weight as you gain strength.