In this section, you should describe the practical methods specific to your research and you should also mention any limitations of the methods used. You should refer to previous work which used the same methods, and give a clear indication of any modifications or improvements in technique. Generally, this section will be written in greater detail in a thesis than that which is usually written in published papers.
Also, if you design a new system or questionnaire or method you must remember to describe it in such detail that another person could replicate your research if they wanted to. This is because it is possible that another researcher may want to repeat your research or use similar methods in the future.
If your research produces items such as tables, charts, and computer programs, it is likely that much of this information will be presented in appendices rather than in this section. It is always useful to speak to your supervisor about what should be in the main body of your thesis and what should be in the appendices.