The easiest way to show what you have found is to just show the raw data. Agree ahead of time what format you are going to use to collect data, i.e., the form you are going to fill out, and just make a display of your data. To do data analysis, easilest technique is to visually examine your data and write a few sentences describing what you have found.

Also the various graphing calculators availible in regular stores can be used to make graphs and to come up with formulas for the graphs. Sophisticated data analysis software is availible as well in software catalogues.

Check out how your work could be assessed in How did you do?