The sub-sections under methodology includes design, participants, apparatus, and procedure. Design gives details of the formal design of the experiment such as whether it was an independent measures design (in which each condition of the experiment is performed by a separate group of participants) or a repeated measures design (in which all participants perform all of the conditions of the experiment). It identifies the independent and dependent variables in the study. Remember, the independent variable is what you manipulate, in your role as experimenter, and the dependent variable is what you measure.
Participants give details of who took part in your experiment. It provides details of their sex, age and any special characteristics of them that might be relevant to your particular experiment (e.g. handedness, bilingualism, etc.). It states whether they were volunteers, whether they were paid for participating. how they were allocated to the different conditions of the study, and of course, how many there were according to that condition.
Apparatus in this context means things like stopwatches, computers, questionnaires, etc. It gives important relevant details (e.g. brand-names and model numbers if the equipment is unusual), but omit trivial and unnecessary details like whether they used an HB pencil or a biro to fill in a questionnaire. Procedure explains how you actually carried out the experiment in practice. Give details of exactly what was done to participants, what they had to do, the order in which tests were administered, and how long test sessions took.