diff --git a/ZeroSSL.com-CA.md b/ZeroSSL.com-CA.md
index cc7a5f5..a809980 100644
--- a/ZeroSSL.com-CA.md
+++ b/ZeroSSL.com-CA.md
@@ -1 +1,23 @@
 Using ZeroSSL.com CA
+
+
+1. Get your External Account Binding(EAB) credentials at www.zerossl.com
+
+2. Register acme account:
+
+```
+acme.sh  --register-account  --server https://acme.zerossl.com/v2/DV90 \
+        --eab-kid  xxxxxxxxxxxx  \
+        --eab-hmac-key  xxxxxxxxx
+```
+
+3. Done.  You can use Zerossl.com with `--server https://acme.zerossl.com/v2/DV90` as normal now.
+
+```
+acme.sh --server https://acme.zerossl.com/v2/DV90  \
+     --issue  -d  example.com \
+     --dns dns_cf
+```
+
+More details: https://github.com/acmesh-official/acme.sh/wiki/How-to-issue-a-cert
+