The following steps will help you to install an Apache web server with PHP and MySQL on your Amazon Linux instance.

I took help of following links to create this guide:

• https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/install-LAMP.html
• https://gist.github.com/keithweaver/546e70bd0c88f4bef49b9051b3ba47bb

1. Launch EC2 Instance:
   • Sign into your AWS account and go to "EC2" service section.
   • In "EC2 Dashboard" click "Launch Instance" button.
   • Select "Amazon Linux AMI 2018.03.0 (HVM), SSD Volume Type".
   • In next screen, select appropriate instance type. You can choose the one which is marked "Free tier eligible" to get started. This can be changed later.
   • Click "Review and Launch" button.
   • During this process, you will asked to select a "Key Pair" to use with this instance. You can either use an existing key pair or create a new one.
   • Download the key pair that you selected. Let's say you saved it with name myserver.pem
   • Launch the instance.
2. Install Apache/PHP/MySQL:
   • On your local system, using the terminal, navigate to the directory where you stored the myserver.pem file.
   • Update permissions for this file - chmod 400 myserver.pem
   • SSH into your instance using following command:
     • ssh -i "myserver.pem" ec2-user@{your public dns}
       • You can get the public DNS by selecting your instance in the "Instances" page
       • 
     • Example:
       • ssh -i "myserver.pem" ec2-user@ec2-xx-xx-xx-xxx.compute-1.amazonaws.com
   • Update your instance:
     •  sudo yum update -y
   • Install Apache, PHP and MySQL:
     • sudo yum install -y httpd24 php72 mysql57-server php72-mysqlnd
   • Start the Apache Web Server:
     • sudo service httpd start
   • Configure the Apache web server to start whenever system boots:
     • sudo chkconfig httpd on
   • Verify the configuration:
     • chkconfig --list httpd
     • It should show following:
       • httpd 0:off 1:off 2:on 3:on 4:on 5:on 6:off
   • Make sure that the security group used by the instance allows HTTP traffic (port 80)
     • https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/ec2-security-groups.html#adding-security-group-rule
   • Go to your Public DNS, it shall show Apache test page similar to following:
     • 
3. Add/update files to document root:
   
   • By default Apache document root directory is /var/www/html and ec2-user doesn't have permissions to update files in this directory.
   • To allow ec2-user to make changes to this directory, we need to change the ownership and permissions of this directory.
   • We will add ec2-user to apache group and then give apache group ownership of the /var/www directory
     • sudo usermod -a -G apache ec2-user
   • Logout and SSH to your instance again 
     • exit
     • ssh -i "myserver.pem" ec2-user@ec2-xx-xx-xx-xxx.compute-1.amazonaws.com
   • Verify that you have been added to apache group:
     • groups
       • It shall list apache in the groups list, such as:
       • ec2-user wheel apache
   • Change ownership of /var/www directory
     • sudo chown -R ec2-user:apache /var/www
   • Provide write permissions to the group
     • sudo chmod 2775 /var/www
     • find /var/www -type d -exec sudo chmod 2775 {} \;
     • find /var/www -type f -exec sudo chmod 0664 {} \;
4. Test your LAMP server:
   • Create a PHP file named phpinfo.php in your server's document root /var/www/html/phpinfo.php
   • It shall just have following content:

     • <?php
       phpinfo();
       ?>

   • In web browser, visit above file using the public DNS of your instance such as:
     • http://ec2-xx-xx-xx-xxx.compute-1.amazonaws.com/phpinfo.php
       • You should see PHP info page similar to following
       • 
5. Configure database server:
   • Start the MySQL server:
     • sudo service mysqld start
   • Execute mysql_secure_installation command to setup root user password and other settings
     • sudo mysql_secure_installation
       • When prompted, enter password for the root user and make sure to save it
         • By default the root account does not have any password so you can simply press Enter when asked for root password
     • Type Y to remove anonymous user accounts
     • Type Y to disable remote root login
     • Type Y to remove the test database
     • Type Y to reload the privilege tables and save your changes
   • To start MySQL server on every boot:
     • sudo chkconfig mysqld on