Creating Chart

Hello All,

I am trying to create a column chart for my daughters swim times. There are a couple of problems. On sheet "Back SCY" when I change the date on row 7 as the rest of them, it totally changes the entire structure of the chart. It adds so many more dates that are not even there with data. I have tried to recreate the chart on other tabs and have come across the same thing. Also, Since I am tracking Olympic times, I wanted to put a trend line or something like that to show exactly where the cutoff is, but the trendline function was not selectable. Any ideas on that one too? It is pretty much the same on the other two sheets as well. My knowledge is little when it comes to Excel, but I am trying to learn. I would appreciate any assistance.

Thank you,

Magoo