Like mammikoura said, it all depends on the distro. Assuming you're on about installing updates, then this is how you do it on Ubuntu studio.
This is the standard screen
From here you select System > Administration > Update Manager.
You will then be presented with the update manager screen.
All you do from here is click check and the OS will check for any available updates, then you just need to click install updates and the OS will do the rest. HTH.