See solution below.
Explanation
You can add private and public IP addresses to an Azure network interface by completing the steps that follow.
Step 1: In Azure portal, click More services > type virtual machines in the filter box, and then click Virtual machines.
Step 2: In the Virtual machines pane, click the VM you want to add IP addresses to. Click Network interfaces in the virtual machine pane that appears, and then select the network interface you want to add the IP addresses to. In the example shown in the following picture, the NIC named myNIC from the VM named myVM is selected:

Step 3: In the pane that appears for the NIC you selected, click IP configurations.
Step 4: Click Create public IP address.

Step 5: In the Create public IP address pane that appears, enter a Name, select an IP address assignment type, a Subscription, a Resource group, and a Location, then click Create, as shown in the following picture:
References:
https://docs.microsoft.com/en-us/azure/virtual-network/virtual-network-multiple-ip-addresses-portal