Mary, I have mainly looked at earlier wills than 1902, and these were in sections by parish, starting with Lonan then clockwise round the Island, which gives you an idea where your will is on the film. The number (131?) will be at the top of the will.
It is also interesting to look at the other wills in the same parish, because you may come across your names in relative's wills. Take photocopies of everything of interest if you can, because when I started I often summarised the wills and regretted later that I didn't have full copies (and give the transcripts to Brian!).

Sue