Ok do this..
Open the Site Manager and select menkom in the Site List and then press Ctrl + \
Now open Notepad or something similar and paste the clipboard, this will paste the exact <site name> that you need, if menkom is in a group then it will add the group names as needed.
For example if menkom is added directly below FlashFXP Sites and not in any group it would paste as \menkom
(Since this is just the site name without any groups the leading slash is optional, if you're wondering why my original example did not include it)
Code:
/tray /overwrite /upload \menkom /localpath="{0}" /remotepath="/public_html/" /quit
If the site menkom is in a group named "websites" then it would paste as \websites\menkom
Code:
/tray /overwrite /upload \websites\menkom /localpath="{0}" /remotepath="/public_html/" /quit
The remote path needs to be the actual path where you want the file to upload, In my original example I gave it a filename but if you want the screenshots to retain their original file name then you omit the name and just define the folder; You must make sure you include the trailing slash if you do this.
Since I don't know the structure of your server I want you to do this, connect to menkom and navigate to the public_html folder, now copy the path from the path box. It might simply be /public_html/ or it could be /home/<user>/public_html/
So now with the correct remote path obtained use it in your Argument.
Code:
/tray /overwrite /upload \menkom /localpath="{0}" /remotepath="/public_html/" /quit