Well, my response to you depends on how much you know about Excel already. In short, highlight the x and y columns in a spreadsheet, click the make chart button, select xy scatter. Make sure the next page has the x's and y's in the right place. I'm leaving out a lot of details, but you should be able to figure it out. After the scatter plot is displayed, right click on a data point and select add trendline. Make sure linear is selected, then move over to the options tab and check the display equation box.
Sorry for the incoherence... I just finished up my homework and now I'm off to bed