You will need to point your domain to the Boomla Infrastructure so that Boomla can serve the website to visitors.
Records already exist
Is there a record with record type A and hostname @? If yes, you can either remove it first or modify it.
Can not use @
Then leave the hostname empty. Also, make sure there is no other record with record type A and an empty hostname. If it exists, either remove it first or modify it.
It is typically provided in seconds, so 3600 means 3600 seconds. Or you can use 1 hour, or any similar value. TTL stands for Time-To-Live. It defines for how long the IP address can be cached by browsers and other servers around the world.