In order to upload your changes to the corpus server you must first export to disk then upload via Lamus.
To export your new sessions and other changes, select the modified nodes or a branch that contains them all and via the context menu (right-click) select export. You will then be offered a location dialog to choose a location on your computer to export the files to.
Lamus is then used to upload the exported files to the server. This process validates all data and file formats before anything is added to the archive.