Creating a local copy of document library is simple and same as adding a network place on your machine.
The steps are very simple. Click on “My Network Place” icon on your desktop and then, click on “Add Network Place”. This will open a new wizard “Welcome to Add Network Place Wizard”. Click “Next” and it will take some seconds to download information from internet. Select “Choose another network location” and click “Next”. A text box will appear with the text caption “Internet or network address”.
Copy the URL of the document library for which you want to create a local folder. This can be done by right click on the document library and selecting “Copy Shortcut”.
Paste that shortcut in the “Internet or network address” and click “Next”. The wizard will ask you the name of the local folder on your machine. Type the name of your choice and click “Next”. A confirmation window will appear with the message of successful creation of the network place. Click “Finish” and folder will be created.
You can copy and paste your documents in the local folders and documents will be automatically uploaded to the site document library. Any change that you make in the local folder will be reflected in the document library.
P.S. local folder will be available when you are online. Nothing will be availabe when offline.