It has been a few since I upgraded but I remember that is was pretty easy. I just re-read the steps and it sounds pretty straightforward. 🙂
http://www.advancedcustomfields.com/resources/upgrading-v4-v5/
1. Backup your database (.sql)
2. If you are using any of the former V4 add-ons than make sure you have access ACF Pro
3. If you developed any “custom field types” then you need to upgrade them: http://www.advancedcustomfields.com/resources/tutorials/creating-a-new-field-type/
4. Add the ACF PRO plugin to your website (drag the advanced-custom-fields-pro folder to the /wp-content/plugins/) folder
5. Activate ACF PRO
6. Deactivate ACF 4 and any premium ACF 4 Add-ons
Then: http://www.advancedcustomfields.com/resources/upgrading-v4-v5/#after-you%20update
What part are you stuck on?
As far as the importing V4 backups into V5, can’t say for sure. Though you could import them into ACF 4 then upgrade to ACF5.
