To import a document, click on “choose a file”. The file explorer of your computer opens, then choose your document. Then, click on “import”. To export an account, calendar, or contacts, select the type of what you want to export, and then the source. (By default it’s set on “all folders”, but by clicking on it, you can select a particular folder). Finally, click on “export”.
If you want more precise criteria, you can click on “advanced settings”. You can then choose the data types you want, as well as the time slot you want. For example, you want to export your calendar but only the month of July. You can choose the calendar and for the date: from 01/07 to 31/07.