diff --git a/README.md b/README.md
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--- a/README.md
+++ b/README.md
@@ -1,4 +1,20 @@
 # Usage
+## do the steps below at the target app directory, not this Orbit module directory(Rails Engine)
+* create kernel/config/initializers/nfu_oracle_config.rb with following content, then `chmod 600` it (do not commit it to git):
+
+```ruby
+ENV['ORACLE_USER'] = 'database user name'
+ENV['ORACLE_PASSWORD'] = 'database password'
+ENV['ORACLE_CONNECT'] = 'host:port/service_name'
+```
 * set cron job to run `bundle exec rake sync_nfu_personal_plugins:sync` for nfu everyday
-* need node
-* sudo apt install nodejs -y
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+
+## Node.js
+* need a supported Node.js LTS version (e.g. 24.x). Ubuntu's own `nodejs` package is 18.x (end of life), install from NodeSource instead:
+
+```shell
+curl -fsSL https://deb.nodesource.com/setup_24.x -o /tmp/nodesource_setup.sh
+sudo bash /tmp/nodesource_setup.sh
+sudo apt install nodejs -y
+```
+* the API server (lib/sync_nfu_personal_data/api/server.js) is started automatically by rake, listens on 127.0.0.1:3000 only, log: lib/sync_nfu_personal_data/api/nfu_api.log
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