Update README.md

@@ -14,9 +14,9 @@ git clone ssh://git@khuhub.khu.ac.kr:12959/2017103956/howsTheAir.git
 3. Install NPM packages
 ```sh
 - cd backend
-- npm install
+     npm install
 - cd frontend
-- npm install
+    npm install
 ```
 4. Enter your API key in `secrets.json`
 {
@@ -24,6 +24,14 @@ git clone ssh://git@khuhub.khu.ac.kr:12959/2017103956/howsTheAir.git
   "googleAPIKey": ""
 }
 
+## Method of Execution
+```sh
+- cd backend
+npm start
+
+- cd frontend
+    npm start
+```
 
 ## external API
 - [kakao map api](https://apis.map.kakao.com/)