Create a Document Library
1. Go to the team site where you want to create a new document library.
2. On the menu bar, click New and then click Document library.
3. In the Create document library pane, type a name for the new document library and, add an optional description. If you want to add a link to the new document library in the left-hand navigation for the site, select Show in site navigation. This option is selected by default.
4. Click Create to create your new document library or click Cancel to return to the team site.
Create a column in a SharePoint Library
1. To the right of the last column name at the top of the list, select + Add column.
2. In the dropdown, select the type of column you want.
3. In the Create a column panel, in the Name field, enter a title or column heading.
4. Enter any other required information. The number of fields will vary with column type you choose. The above example is for a "number" field.
5. Select Save.