Where do I find emails and how do I open them

You can sign in with Apple ID and password used in your device from a web browser at www.icloud.com and view mails Read email in Mail on iCloud.com - Apple Support

The mails will be received in inbox , select the mail ( click once over the mail to open it ) , in case if you are using only a web mail account , sign with mail address and its password and view the mail .

Who is your email provider? What device are you using?

The generic answer is that you add your email account to your device and then use an email app to read the email. However, without more details from you, it's really not possible to give you a more detailed answer.