在openvpn中，如何新建client2.crt和client2.key文件？

luckypoem

as3:/etc/openvpn/easy-rsa/2.0# ./build-key client2
  Please edit the vars script to reflect your configuration,
  then source it with "source ./vars".
  Next, to start with a fresh PKI configuration and to delete any
  previous certificates and keys, run "./clean-all".
  Finally, you can run this tool (pkitool) to build certificates/keys.

提示要编辑vars文件，不知该如何编辑？我创建client1.crt和client1.key成功，这个vars文件是对应client1.crt和client1.key的吧，如果是的，那该如何再次修改vars文件呢？