Hello
Upgrading an SAP system to a newer release involves many steps.
You need to make sure whether OS and Database is compatible for the target release.
You need to create a stack file using the Solution Manager Maintenance Optimizer
Download the upgrade guide from http://service.sap.com/instguides
Read the upgrade guide and prepare the system for the upgrade.
Download the upgrade tool and start the upgrade once all the pre-requisites are in place.
Regards
RB