there is no functionality to upload images from computer,
as far as I can see ....
Can you give an example? Where do you want to upload images? (I upload to sharing sites with a browser. Ftp/sftp would work in other cases. I drag/drop onto an NFS mounted drive. I assume there is some other use-case but I can't think what it would be.).
Correct - you cannot upload an image to this forum. However you can link to one hosted somewhere else.
For screenshots I use ksnip - which allows you to very simply upload grabs to imgur like this
APTUS Centre.
The beauty is that no imgur account is required and you don't have to faff around resizing to 50x50px or whatever.