diff --git a/README.md b/README.md
index 9da5f7c..d88c895 100644
--- a/README.md
+++ b/README.md
@@ -1,4 +1,53 @@
-casp
-===============
+CasP
+=====================================================================
 
-CasP - Cloning Automation System for Programming learners
\ No newline at end of file
+CasP - Cloning Automation System for Programming learners
+
+CAUTION
+----------------------------------------
+This script will initialize your storage on running PC wihtout queries.
+Use this script on erasable HDD/SSD/FlashDisk.
+
+ABSOLUTELY NO WARRANTY.
+
+
+Usage
+----------------------------------------
+To Clone running NetBSD8(or 9) system:
+````
+sudo zsh -f root/clone_me_gpt
+````
+
+Typical using situation is:
+
+![Cloning](img/cloning.png)
+
+> You have installed NetBSD8 and several applications on certain PC.
+> Then, invoke clone_me_gpt.sh after plugging USB memstick.  This script
+> clones your NetBSD8 environment belonging in / and /usr paritions.
+
+
+Cloning is done with steps of partitioning and copying.
+Thus, two storage sizes can be different.
+Of course, target storage should be bigger than file hierarchy
+size in source storage.
+Note that be careful of privacy information because user account and system
+settings in /etc will be also copied to new system.
+This script is created with intention of making it much easier to
+share learning environment with friends.
+
+NetBSD environment is one of the best choice to simplify construction of
+educational software environment.
+
+Requirements on source PC
+----------------------------------------
+Item		| Configuration
+------------|-------------------------------
+zsh			| Located as "/bin/zsh"
+fvwm2		| Located anywhere in $PATH
+kterm		| Located anywhere in $PATH
+ruby		| Located anywhere in $PATH
+
+Any item can be altered to any equivalent one.
+In that case, rewrite command names in each script to preferable ones.
+