Is this heart pain? I am 21 an for a few wees I have been haveing chest pain in the center of my chest. I am a smoker so coud it be my lungs?

No way to know. At your age, heart disease is unlikely but not impossible. Most chest pain in young people is related to muscles in the chest wall. The diagnosis of chest pain requires a full history by a well-trained health provider, a physical examination and often lab tests, including a chest xray and ECG in some cases. Nobody can diagnose it on the basis of a brief description. If you are worried, see md.
Chest. Chest pain can be caused by many different things. You are right in the fact that your lungs could be the issue. Often times smoking causes lung problems such as asthma and bronchitis. In addition to pain in your chest you would also likely have a cough and/or wheezing if this was the issue cardiac (heart) problems are also a possibilty, this includes severe conditions such as an aortic dissection (tearing of a major artery in your chest) or even angina (chest pain when your heart does not get enough oxygen). In addition, common problems such as anxiety, heartburn, costochondritis (inflammation between the ribs) can be the cause. As you see there are a lot of possibilites, it will be up to your doctor to take a detailed history, exam, and testing to figure out where your pain is coming from. Good luck.