Unfortuntately the Steemit site does not do notifications, although it did at some point. You can use https://partiko.app/referral/steevc mobile app or https://busy.org/i/@steevc as a web interface or https://esteem.app/ that has mobile and desktop apps and all have notifications. You just log into those with the same key.

I tend to use a mix of these, so I may get notifications from an app, but still use Steemit to write posts and comments.