How do you save and continue on the 20 level free trial on World of Warcraft

The free trial allows you to reach level 20. It also allows you to have 10 gold, no more. If you want more gold, you will have to either continue with a paid subscription, or start another character. The normal limits of 50 characters per account and 10 characters per server apply, but you can only have 10 gold per character.