1.https://trailhead.salesforce.com/content/learn/modules/starting_force_com/starting_intro
challenge:
1.右上角 
选择setup
2.选择Object Manager
3.选择contact
4.选择Fileds &Relationships
5.选择new
6.选择Currency,点击next
7.next，next，save
8.最后确认
来源：oschina
链接：https://my.oschina.net/bechange/blog/4702833