See attached files please.
To use the Fourier tool in Excel you need to load the Data Analysis tool pack in Excel first. So in the current spreadsheet you should go to "Tools", "Add ins", Select "Analysis Toolpak" then click OK.
To perform tha Fourier analysis go to "Tools", click on "Data Analysis" and select "Fourier" from the list
Select the range of cells that you need to perform the analysis on, in this particular case cells of current sampekls in cells B2 to B1025. Note using Ecel Foirier analysis tool this must be a whole power of 2 ...
Using a set of sampled waveform data Fourier tools are used in Excel to generate fourier coefficients hence produce spectrum graphs identifying key frequency components in the data, and more.