You need to first login with your registered account and then you will be directed to the dashboard.

Then click on Notifications > New Notifications

Add the notification title, message, and URL and change the image (if needed).

If you wanna personalize your message you can either send a notification ith user's name on it or else on a specific festive occasion. 

Select the notification duration and scroll down

Then in Scheduling options you can schedule your notification and send it now else you can change the date and time. 

Click on Advanced Option and then enter the fields in segment options.The notification will then be sent to selected users.

In this manner, you can personalize a message. Other than this you can also send notifications to your users on their birthday telling them about some special offer or else you can remind users to complete the purchase if they left anything in their cart. This can be done basically with e-commerce websites.