For example, let's say we want to download the structure of BSEG table
into a .xls file so follow these steps.

1.        Goto SE11 Screen.
2.        Write the table name 'DD03L' into database table field and
        press display button.
3.        Select Display Table contents from Utilities menu.
4.        In selection screen you can give the table name you want to
        download in Tabname field(i.e. BSEG).
5.        If you want all details of each field then execute transaction
        as is otherwise select 'List Format->Choose fields' from the
        settings menu to select the fields you want in display.
6.        It will give you the details of all the fields in that table.
7.        For Downloading these details, goto Edit->Download and follow
        the usual procedure for download.