Please add valid username and password in the following excel path :
Go to "test_Data" folder.
Open "testData.xlsx" file.
Make desired changes in "Login Details" sheet.
Under username remove "dummyUsername" and add your username for E-commerce site.
Under password remove "dummyPassword" and add your password for E-commerce site.
Under "Product Selection" sheet: (A) If you want to remove "dettol hand wash sanitizer" with your favourite product name. (B) Else don't make changes to it.
If you want to change the browser from firefox to chrome: Just replace browsername in testng.xml from "firefox" to "chrome" and vice versa.