Plotting 2 lines on a line graph

Hi all,

I am trying to plot 2 lines on a line graph, and I'm having trouble doing it - hoping you guys can help.

In column A I have row numbers, counting how many entries I have.
In column B I have cumukative profit
In column C I have exposure

Y axis is where I am having the problem.

What I want is to do is have 2 lines tracked against each other. I have attched a file showing what I currently am getting, and also a jpg image in the workbook showing my current graph (that works). Essentially I want this graph to just have another line on it showing exposure, but i cant figure it out.

Notice on the one I've tried it goes up to like $900 for some reason.

Could anyone help me out?

Thanks