See Patholines:Copyright for information regarding what images you may upload.
Upload to Wikimedia Commons
Upload to Patholines server
This is recommended if the image is likely relevant only for Patholines:
Adding uploaded images to articles
Images can be added in articles by clicking the "Edit" tab at top and then "Insert" and "Media". Alternatively, by "edit source", a source code is provided after having uploaded an image, which can be copy-pasted into articles. In source code, images are added to the right in the text by the following code for an example file:
[[File:Patholines logo.png|thumb|150px|Image description.]].
See also: Wikipedia:Extended image syntax, for how images can be customized in articles.