Managing trash
To access the trash can, just click on its icon, to the left of the top bar containing the path to the files.
There you will find the list of previously deleted files.
Restore files
To restore a file, just right-click on it, or go to the File Actions menu after selecting it, and choose "Restore". The file will be moved immediately to its original location, which is mentioned next to its name.
Erase files
Also accessible through the right click or the File Actions menu, this function allows you to definitively delete a file from your drive. Be careful, any file destroyed this way will be irretrievably lost.
If the folder(s) in which the file was located at the time of its deletion no longer exists, this folder structure will be recreated during the restoration.
Accounting for files in the trash can
Keep in mind that as long as the files have not been completely destroyed, they will still be included in the total size of the files in your drive.