Before you download D-Lab please check the hardware requirements.
Than download the latest D-Lab setup here and follow the installation wizard. To run the software a valid licence dongle is required.
In case you already installed a previous version make sure you have a backup of all your data. Afterwards follow the same procedure as for the first installation.
Updating a D-Lab 3.0, 3.01 of 3.10. please this additional information here.