The ESET software should update itself without any intervention, however should you wish to manually update the software, please do the following

1 - Load up ESET Endpoint AntiVirus. This can be done by clicking on the Endpoint Antivirus icon on the taskbar
2 - Double click on this icon and the program will load
3 - Click on Update
4 - Click Update now
5 - The software will download the latest signature database information and load it into the software