What are the basic beliefs of buddhism

The basic doctrines of early Buddhism, which remain common to all Buddhism, include the "four noble truths": existence is suffering ( dukhka ); suffering has a cause, namely craving and attachment 

"The main beliefs of Buddhism are reincarnation, the four noble truths, the five precepts and the three trainings or practices. Buddhism also includes an eightfold path that was made by the Buddha and helps lead people toward enlightenment.
LONGER VERSION OF ANSWER:
Buddhists believe in reincarnation, meaning that they believe that people are reborn again after dying. They believe that people constantly go through the cycle of birth, living, death and rebirth.
The three trainings or practices in Buddhism are sila, samadhi and prajna. Sila is the practice of virtue, morality and good conduct. Sila is the classic "golden rule" of Christianity, do unto others as you would wish them to do unto you. Samadhi is the mental development of the person and references to focus and meditation. Buddhists believe that developing one's mind is the best way to lead to personal freedom. Prajna is the discernment or enlightenment in which wisdom emerges into a person's calm and pure mind.
The four noble truths of Buddhism explore human suffering. The first is Dukkha, which is that suffering exists. It states that suffering is universal and everyone is bound to suffer. The second is Samudaya, which is that there is a cause for the suffering that everyone experiences. Buddhists believe that the desire to have and control things is what leads to suffering. The third is Nirodha, which is that there is a stop to suffering. Buddhists believe that in achieving Nirvana then the mind is free to experience complete freedom and non-attachment. The fourth is Magga, which is that the eightfold path is the way to end suffering." 
                                                                  -Answers.com

I got the answer from Answer.com which I quoted, for I am not religious and I don't really know a whole lot about religion. It's a handy website, good luck on your assignment. :)