Just unpack it to somewhere in your computer.
Open Excel, select from menu: 'Service', then 'Add-In'.

Then
to insert the file ta-lib.xll to the list which was opened
(because you press 'Add-In')
choose the file's location by pressing 'Browse',
then find this file (ta-lib.xll).
Make sure that 'ta-lib' was added in.

Then you may close everything if you want.

In the file example.xls
you will see the examples of indicators (examples only).
And in the file func_list.txt
you may see the list of the functions available
(to work with this indicators).

So, just open your Excel (with your data) once again,
press Shift-F3,
and you will see the master of function's menu,
select indicator and so on.