How to link to part of imagery when you for instance need other mappers advise?
You need to upload the image to a server like https://imgur.com/upload then paste the link into your query here.
So the procedure is to take a screenshot of whatever one would like the other mapper to look at, upload it to imgur and
then ask for assistance through a post to the forum?
Any other alternative not involving parties outside OSM?
The help-website has the possibility to upload images. (http://help.openstreetmap.org)
What kind of imagery, do you have in mind, Honning?
As an example : Mapping in JOSM using Bing imagery I run into a problem and would like other mappers advise. Then it would nice to guide them to the area that causes the problem and maybe also provide a snapshot of the imagery.
To referrence to a specific area, you can read the coordinates of the mouse-pointer in the lower left corner of JOSM. You can also copy the coordinates of a node to your clipboard by pressing Crtl-Shft-C.
Please have a look at https://wiki.openstreetmap.org/wiki/Browsing#Sharing_a_link_to_the_maps. Lots of options explained in there
See also https://blog.openstreetmap.org/2014/12/01/new-query-feature/ for how to find and link to specific map objects.
If you want to discuss the content of the imagery you could also right click on the background, click Show tile info and click on the tile link. This open the tile in your webbrowser. You can share this tile link then.