What Are The Main Teachings Of Buddhism?

Mental suffering can be overcome.  It is up to each person to try to overcome one's own suffering, by following the Buddha's wise suggestions..

The Buddha advised,
"Do no evil
Do what is good
Purify the mind."

Examples of "evil" are actions such as killing, stealing, adultery, lying, speaking cruelly, and other actions that harm oneself or others.  Examples of "good" are actions such as abstaining from evil actions (remaining harmless), doing things to help others, and trying to improve one's own personality (by associating with wholesome friends, reading spiritual literature, meditating, reflecting on one's actions, being mindful, and more).

"Purifying the mind" means developing wisdom (not just knowledge) to overcome all greed, aversion, ignorance, pride, anger, conceit, lust, jealousy, dishonesty, and all other downsides of the heart/mind.

The Buddha taught a path to happiness, the same path he taught for achieving full enlightenment, called the Eightfold Path.  It starts with understanding the law of karma (that "what goes around comes around" and we eventually pay for all our bad actions, and eventually enjoy good results from good actions).  

For more information, see this great website: www.justbegood.net