To fit a curve to data, the data must be entered in an Excel file.
The data must be in two columns next to each other. If your data are not in two adjacent columns, you must work in Excel (or the program that created the Excel file) to re-arrange the data. In Excel, Copy and Paste are very effective for moving columns of data. Hiding the columns in between will not help.
If your data have come out in rows, and if you are good with Excel, try the Transpose function to move them into columns.
Exponential Curve Fitting finds numbers A and B to make a formula y = Aex
The numbers in your first column are the x; those in the second column are the y.
Polynomial Curve Fitting also uses the first column as x and the second column as y.
More on curve fitting