All your saved flows are available in the panel on the left of your canvas. Flows can either be listed individually or grouped into folders. To view the list of flows contained in a folder, click on the folder. You can also search for a specific folder or flow using the search bar at the top of the list. To open a specific flow in your canvas, simply click on it from the list. You will now be able to edit the flow and save your changes. To edit the details of individual nodes, simply click on the node and edit the information in the panel on the right.
Note: currently, the only way to create a folder is to add a new 'blank' flow and saving it using the name of the folder you want to create. In your flow list on the left, right click on the flow you want to move to the folder. Select 'Move' and then select the 'blank' flow you've added before. This 'blank' flow will now convert into a folder containing your flow.