Thread:Old McDonald/@comment-26231946-20150704175753/@comment-24494906-20150704190046

Use Special:Upload, select the file you want to upload and use a meaningful destination file name. Also select the appropriate license.

Or if you want to add a new version of a pic (and replace the old), you can also go on that pic's site and choose "Replace". (But it should be basically the same pic, then.)

In the corresponding article, you just add a link to the image's site. Like looks like this:

Or if you want to determine its size, use, then the pic is 300px wide.

I use the classic editor to make my edits, no clue how this works in the visual editor (especially since the character boxes are templates). The field to edit in the character box is the "image" field.