To create a gallery for an article, first click on the “Add Media” button in the article editor. 

In the screen that opens, on the left hand side, click on “Create Gallery”. 

Now choose the pictures to be included in the gallery by clicking on each picture, a tick will be placed showing the image is selected. 

Once you have your images chosen, at the bottom right of the page click on “Create a New Gallery”.

On the right hand side in the options, make sure that “Link To” is set as “Media File”.  Also choose how many columns.  The thumb nails will be resized to fit the width of the page.

Once the above options are set, on the bottom right of the page click on “Insert Gallery”.

Now click on the Update button to save the page.

If you need to change anything, click on the gallery in the editor, then the edit button and delete button appears, click on the edit gallery button.

The gallery below was created as above.  It has a 4 column layout.