How to add column in document library in SharePoint 2013

Question

I am trying to make a customized site Content and I have made it successfully on Document library.While uploading it gets uploaded well but the by default behavior of document library shows me three but default column which is there in the image

1)Name 2)Modified 3)Modified By

I want to add 4th Column with user input named as a description. Image is as follows:

Now how do i add 4 th Column on User Input while uploading the file.

Answer 1

• If the list or library is not already open, click its name on the page or in the Quick Launch.

  • If the name of your list or library does not appear on a page, click Settings Office 365 Settings button , click Site Contents, and then click the name of your list or library.

  • In the ribbon, click the List or Library tab.

  • The library and browse tab on the ribbon In the Manage Views group,
    click Create Column.

  • SharePoint Online Library create column link In the Name and Type
    section, type the name that you want for the column in the Column
    name box.

  • Under The type of information in this column is, select the type of
    information that you want to appear in the column. For more on column types, see Site column types and options.

  • In the Additional Column Settings section, type a description in the Description box to help people understand the purpose of the column
    and what data it should contain. This description is optional.

  • Depending on the type of column that you selected, more options may
    appear in the Additional Column Settings section. Select the
    additional settings that you want. For more on column settings, see
    Site column types and options.

  • You can add validation to make sure the column entry matches what's
    expected. Click Column Validation to expand the section, and type the Formula that you want to use to validate the data. Add a User message that describes what valid data should look like to help users enter
    valid data. For information on validation and formula syntax see
    Examples of common formulas in SharePoint Lists.

  • Click OK to save.

please check the below link Create a column in a SharePoint list or library for step by step approach

If you want to change the columns in the view please check the below msdn link Show or hide the columns of a list, document library