Before following the below steps generate a key.jks file using this command source
MacOs/Linux
keytool -genkey -v -keystore ~/<path where key needs to be generated>.jks -keyalg RSA -keysize 2048 -validity 10000 -alias upload
Windows
keytool -genkey -v -keystore c:\Users\USER_NAME\upload-keystore.jks -storetype JKS -keyalg RSA -keysize 2048 -validity 10000 -alias upload