The whole project library is accessible to you via this option:
This section will include your source files as well as the reference materials that have been provided for your job:
You can also include attachments (invoice, external documents) to support your work.
Working offline:
To continue your work offline you will need to configure an export with the relevant information for your task. Then, you will be able to import the file again and all the information will be loaded in the Editor.
Note that as a user you might have some restrictions to work offline. If you have any doubts, check with your project manager or administrator the details of your user rights.
For more information about format compatibilities check the page using the new XLIFF format to work offline.