The easiest method in excel is to load up the chart wizard.
Chose the type of plot you want (most likely XY scatter in these cases), click next.
And then when it gives you the Data range selection, instead of using that on the tab at the top select "series". You can use that to add multiple data sets, and it allows you to easily individually select the x and y values. The easiest method to select the X and Y values, is to click the icon on the right of the location for the X and Y values, and just highlight the data you want it to be. When you are done click that icon again.