The Nibbana discussed above is the Truth of the Extinction of Suffering. Your question on how to reach the realm of Nibbana falls under the category of the Truth of the Path Leading to the Extinction of Suffering (Magga-sacca0. Magga-sacca takes Nibbana as its goal, the elimination of the basic distresses of birth and death as its objective and uses as its method the Threefold Learning (Ti-sikkha), which considers of morality or moral precepts (Sila), concentration (Samadhi) and wisdom (Panna).
⑴ Morally aims at preventing faults in the three kammas of body, speech and mind. There are three levels of moral precepts to follow: the five precepts, the ten precepts and the complete precepts for the higher ordained. The five precepts are followed by both lay believers and monastic deiciples, that is, abstinence from taking life, from stealing, from illicit sexual conduct, from false speech and from intoxicants. The ten precepts are followed by novices who have just renounced lay life. (Novices are usually under the age of 20 and will get higher ordination to become monks or nuns at the age of 20.) The complete precepts are followed by monks and nuns. At the beginning of the establishment of the Sangha Order, there were no fixed rules set for the whole Order. Afterwards, precepts were laid whenever problems arose. By the time of the Buddha’s Parinibbana, there were more than 200 rules. The Bhikkhu precepts now number 227 in Theravadin countries, 253 in Tibet and 250 in Han-inhabited regions of China. There are mostly the same, with slight differences in grouping of certain items. There are 348 rules for bhikkhunis in the Han rigions.
⑵ Meditation or concentration is a peaceful and tranquil state of mind neither drowsy nor perturbed. It is a necessary practice for general religious practitioners in India, especially for Buddhists in their cultivation. With concentration, the practitioner can distance himself from coarse distinctions of rapture and joy in the body and mind, depart from sense desire, and gradually develop ease and peace of body and mind, and finally place mind or thought in any chosen state, tranquil, stable and undisturbed. Such meditation can lead to the acquisition of a pure and correct wisdom. Regarding meditation, there are four stages of trance and four higher stages of non-material trance within this world; and there are nine stages of meditation beyond this world. Through meditation or concentration, wisdom can be acquired.
⑶ Wisdom enables one to distinguish the self-nature of all dhamas from their common characteristics, to fully understand the theory of the Four Noble Truths, and thus has the function of dispelling illusions and attaining truth.
The Threefold Learning of morality, concentration and wisdom are emphasized in the practice of the thirty –seven ways to enlightenment, which are the four Foundations fo Mindfulness, the four Right Efforts, the four Roads to Power, the five Spiritual Faculties, the five Mental Powers, the seven Factors of Enlightenment and the eight-fold Path. I will not discuss each in detail here, but I will say something about the eight-fold Path:
⑴ Right View is to see manifest in every dhamma the theories of Impermanence, Egolessness, Dependent Origination and the Four Noble Truths and make them as one’s own knowledge;
⑵ Right Thought;
⑶ Right Speech;
⑷ Right Bodily Aciton means to be guided by the right view in daily life and behavior, so the body, speech and mind are in a conformity with the law of Dhamma;
⑸ Right Livelyhood means to make one’s living in proper ways and oppose the vicious life of supporting oneself by swindling and defrauding others of their properties;
⑹ Right Effort is to strive after the goal shown by the right view without let-up in actions of body, mouth and mind;
⑺ Right Mindfulness is to always keep the Right View in mind, bring it to mind frequently and never forget it;
⑻ Right Concentration is to practice under the guidance of the Right View, to enter the state of pure and undefiled meditation. (From Essentials of Buddhism: Questions and Answers)