You can create a folder structure in a workspace in the Files section. You can use these to organise files in the same way as would on your computer.
Something else we've added is labels - these are a much more powerful way of organising your files (and tasks). The idea behind them is that you can have a single file (e.g. an employee induction template) that doesn't need to be added to multiple folder locations e.g. HR Forms, New Employee Documentation, Sales, Finance etc. It makes organising and locating files much quicker.
Labels explained
Labels are tags which you can apply to any or all files. They are completely customisable which means you can choose as many labels per document as required. By assigning labels you visually group documents/files of the same type together and when you click on a workspace Files section you can browse or search by label.
Clicking on a label will bring up all of the documents/files with that label - essentially providing you with a sub folder.
Click here for more information on labels.