Somebody explain it to me because over the years of self development free of outside influences, I've lost the ability to grasp the concept.
What is good, and what is evil?
Good: What an individual or community considers to be a benifical and positive action or outcome.
Evil: What an indivdual or commiunity condisders to be a malicious and negitive action or outcome.
Is good worth pursuing?
Is evil worth pursuing?
Individuals and communities will always pursue what they consider to be good and avoid what they consider to be evil. Communites, however, suffer from dissent.
What are the differences, and similarities?
This depends on the individual in question's subjective opinion.
Why are things that are considered pleasant also considered evil?
And why are unpleasant things good?
This is not always the case, and depends on who you ask. This observation most likely (I assume you live in North America or Europe) comes from the strong presence and history of Christianity in the first world. Many sects of Christianity strive to obtain a greater reward after death by ignoring the pleasures of our world. The logical progression of this thought is that if pleasure leads to sin, then unplesureful things lead to grace. Thus, you may have picked up this impression, your own thoughts on the matter nonwithstanding.
What makes good good and evil evil?
Nothing. Good and Evil are subjective, no way set in fact.
Why I don't have the same morals as anyone else?
Different input leads to different output. Your life has brought you to conclusions on Good and Evil, same as everyone else. People can come to wildly different conclusions, as a look through politics and history can show you without doubt.