OK, so you've created a bag and managed to add a file to your bag - great! You are now it's proud owner. Don't forget to register it first!
Here's a simple overview of most common operations you can do with your bag:
View items in the bag by clicking on them
Download an item using the arrow-down icon
Delete an item using the trashcan icon
Select multiple items using the selector circle icon in front of each item
Add item using the "Add item" button
Share the bag using the "Share bag" button (or via the 'hamburger' menu on the left). Check here for more details on sharing modes and sharing channels.