Just in addition to Rodrigo's answer, here you can find a guide that covers the steps to get your instance upgraded: https://confluence.atlassian.com/display/DOC/Upgrading+Confluence+Manually
In your case you could go straight to the latest version if you wish.
Feel free to raise other questions on this forum or a ticket on our support channel (http://support.atlassian.com) if you have any questions regarding the upgrade process.
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