ownCloud 6 comes with a fantastic Mozilla Sync option that allows you to synchronise your Firefox bookmarks and other settings with your ownCloud instance rather than using Mozilla or another less credible third party provider. This is how I set it up:
In your ownCloud Instance:
Enable Mozilla Sync if you haven't already
Click on your username in the top right-hand corner
Click on Personal
Set your email address in owncloud (if it's not done already)
Scroll down to Mozilla Sync where you'll find the information required to configure Firefox.
In Firefox on Your Desktop
Open up Firefox preferences
Select the Sync icon
Click on Setup Firefox Sync
Click on Create a New Account
On the Account Details window:
Select: Use a custom server...
Enter your email address as per Mozilla Sync in ownCloud
Enter your ownCloud password
Enter your server address as per Mozilla Sync in ownCloud
If you entered your credentials correctly, you should be returned to the Sync tab in Firefox preferences.