README: add description how to work (when fork)

README.md

@@ -6,6 +6,42 @@ Golang execution layer implementation of the Ethereum protocol.
 
 Orakle open-source EIP team repository.
 
+## How to Work
+
+### If fork
+
+the case for working on personal repository after fork (recommended)
+
+1. Setting for the first time
+
+```
+// add remote upstream
+git remote add upstream https://github.com/orakle-opensource/EIP_opensource.git
+```
+2. Working on personal repository
+```
+// create branch to work
+git checkout -b [branch_name]
+
+// rebase upstream commits into branch
+git rebase upstream/master -i
+
+// staging and commit
+git add .
+git commit -m "message"
+
+// push
+git push -u origin [branch_name]
+
+// go to upstream repo(https://github.com/orakle-opensource/EIP_opensource.git) and create pull request
+```
+3. After merge pull request
+```
+// checkout master and pull upstream commits
+git checkout master
+git pull upstream master
+```
+
 ## License
 
 The go-ethereum library (i.e. all code outside of the `cmd` directory) is licensed under the