How do I access my iCloud mail account?

To access iCloud mail from an internet browser or from an Apple device, see instructions in Set up iCloud Mail on all your devices - Apple Support

To access mail using a 3rd party mail application, see: iCloud Mail server settings for other email client apps - Apple Support

You can also just goto iCloud,commin any browser.

Just to follow up on @FoxFirth point of accessing you iCloud Mail via a Third Party Mail application

Sign in to apps with your Apple Account using app-specific passwords

You will be required to create an Application Specific password via the instructions is above link

Or, as also suggested by @ BDAqua, go www.icloud.com

You are welcome

Do come back to these forums in the future if / when additional question may arise