Welcome to Inkipedia!
To add an image, the basic syntax is
[[File:filename.extension|location|size|caption]]. So if I wanted to add File:Splatoonlogo.png to the right-hand side of a page with a size of 100 pixels wide and with a caption that says "This is the Splatoon logo", I would type
[[File:Splatoonlogo.png|right|100px|This is the Splatoon logo]]. Full details as well as plenty of examples are available on the help page mw:Help:Images. If you want to see how an image was placed on a specific page, just hit the "edit" button on that specific page to see how they did it. Heddy (talk) 08:27, 15 April 2018 (UTC)