LOOK AT A PICTURE FIRST, you might be confused if you read this first.... I think the easiest way to figure it out is to search on google, and just look at google images... but a tape diagram (from what I can see) is best used in a situation with a ratio. you draw out the ratio, such as 5:3 (which is from the picture I'm looking at) and then, than add up the ratio, divide it from the total they give you, thus giving you the amount each section of the tape is worth, than multiply that by the numbers of the ratio given....