diff --git a/.gitignore b/.gitignore
index 1f57b97..9aad7a2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1 +1,3 @@
 /output
+/customizations/users.table
+/customizations/overlay/
diff --git a/README.md b/README.md
index bff126c..dee2e36 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,19 @@
-SystemAgent - Base system port
+# SystemAgent - Base system port
+
 This is the project for SystemAgent compatible SBCs.
+
+## How to build the same image
+
+* Clone buildroot repository.
+* Set `BUILDROOT_PATH` environment variable accordingly.
+* Run `buildroot_make.sh xxxx_defconfig` (see `configs`).
+* Run `buildroot_make.sh nconfig` to make your changes.
+* Run `buildroot_make.sh` to start your runs.
+
+## Necessary modifications
+### Add new users
+Edit users.table in `customizations` directory.
+
+### Copy whatever you want into the filesystem
+Add them to the `customizations/overlay` directory, if the directory does not exist, create it.
+
diff --git a/configs/orangepi_pc_system_agent_defconfig b/configs/orangepi_pc_system_agent_defconfig
index cec3ca7..e5258dc 100644
--- a/configs/orangepi_pc_system_agent_defconfig
+++ b/configs/orangepi_pc_system_agent_defconfig
@@ -20,6 +20,8 @@ BR2_SYSTEM_BIN_SH_BASH=y
 BR2_SYSTEM_DEFAULT_PATH="/bin:/sbin:/usr/bin:/usr/sbin"
 BR2_GENERATE_LOCALE="en_US.UTF-8"
 BR2_TARGET_LOCALTIME="Asia/Tokyo"
+BR2_ROOTFS_USERS_TABLES="$(BR2_EXTERNAL_system_agent_PATH)/customizations/users.table"
+BR2_ROOTFS_OVERLAY="$(BR2_EXTERNAL_system_agent_PATH)/customizations/overlay"
 BR2_ROOTFS_POST_IMAGE_SCRIPT="support/scripts/genimage.sh"
 BR2_ROOTFS_POST_SCRIPT_ARGS="-c board/iminc/orangepi-pc-system-agent/genimage.cfg"
 BR2_LINUX_KERNEL=y
@@ -46,6 +48,7 @@ BR2_PACKAGE_NETWORK_MANAGER_TUI=y
 BR2_PACKAGE_NETWORK_MANAGER_MODEM_MANAGER=y
 BR2_PACKAGE_OPENSSH=y
 BR2_PACKAGE_BASH_COMPLETION=y
+BR2_PACKAGE_SUDO=y
 BR2_PACKAGE_VIM=y
 BR2_TARGET_ROOTFS_EXT2=y
 BR2_TARGET_ROOTFS_EXT2_4=y
diff --git a/customizations/users.table.example b/customizations/users.table.example
new file mode 100644
index 0000000..d2edb46
--- /dev/null
+++ b/customizations/users.table.example
@@ -0,0 +1 @@
+# See https://buildroot.org/downloads/manual/manual.html#makeuser-syntax for documentation.
diff --git a/external.desc b/external.desc
index f1c7462..d402d5a 100644
--- a/external.desc
+++ b/external.desc
@@ -1,3 +1,3 @@
-name: orangepi_pc_system_agent
-desc: System Agent port for OrangePi PC
+name: system_agent
+desc: System Agent base system