At this point you should already be connected to your EC2 instance with Putty. Follow the steps below to install updates (upgrade packages) on your instance.
From the Putty window, run the following command to update the package index:
sudo apt update
Wait for the package index to finish updating. Once it's done, you'll be returned to the command prompt.
Run the following command to upgrade the packages:
sudo apt upgrade
When prompted to continue, type Y and then press Enter.
If you are prompted about whether or not you want to keep existing files, then just press Enter to keep the existing files.
Wait for the upgrade process to finish. Once it's done, you'll be returned to the command prompt.
Run the following command to reboot the instance:
sudo reboot now