A upgrade from VEEAM version 5 to version 6 is easy to do and if you read good and follow the instructions less problems will occur. Start first to download the software from htttp://www.veeam.com.
When downloaded you can start the setup.
Click on Yes to upgrade the current version.
Click on Next
Accept the license agreement.
search for the license file you have from VEEAM ( this could be a trial version )
When located the license file click on Next.
Select the software option you want to install on the server.
Verify if the SQL server and instance are correct and click Next.
You get the question that the database need to upgrade. ( click yes to continue )
Enter the administrator credentials who has the database owner rights.
Leave the settings to default and click on Next.
Create a shortcut on the desktop and click on Install.
Wait until the installation is finished.
When finished click on Finish
After the installation is finished you have to restart the server.
After the reboot you should verify if all configuration from version 5 are in version 6 if yes. continue to install a patch for VEEAM 6 ( this one is required )