Step 1 : Download node and install https://nodejs.org/en/download/ .

Step 2 :  Open Command line for Windows as Administration mode and Terminal for mac/ linux.

Sote ::  For mac and linux please add

 sudo 

if the commands in bellow are not works.

Step 3 : Install npm

 install npm 

Step 4 : Initialize react native

 npm install -g create-react-native-app 

Step 5 :  Go to your any project directory and create new project named FirstProject.

  create-react-native-app FirstReactProject 

Step 6 :  Go to your newly created project directory.

 cd FirstReactProject 

Step 7 :  Run Project.

 npm start 

Step 8 :  For Android Phone . Go to play store and install expo in your android phone.

Step 9 :  after start project a QR will be generated on command mode .

Step 10 :  Open expo in android/ios phone and scan the QR code.

And That’s All . If you are mac user then there may have the following problem in npm run .

Here is the Solution.