In order to have the following pictures side by side below – and not vertically aligned – first upload them to the Media Library and then click to the Add Media button above the page editor (click on the screen capture to display full size):
This brings us to the Media Library where multiple images may be selected at once by keeping the Ctrl key pressed and then select the “Create Gallery” menu at the top left side and click on “Create a New Gallery” at the bottom right:
A new window with settings for the Gallery is opened where it is possible to choose 3 different settings.
It is recommended to link to the “Media File”, then specify how many columns and then the size for them, probably “thumbs” otherwise a medium size depending on what is needed.
The result will be as follows:
If there are only a couple of images and a Gallery as above is not really needed, it is also simply possible to select just some images the same way and go to their respective settings at bottom of the left sidebar, one by one, and set them as illustrated:
Alignment: None, Link to: Media File, Size: Thumbnails – what counts here the most is the alignment to be set to “none”.
We then get the following result depending on the screen size and the theme’s thumbnail sizes:
The amount of images used is not important and you can achieve the same results with just 2 pictures for instance. It all depends on your page layout and how it will look in responsive more.