The site definitions are defined in the reporter.sites table on the NFA Console server.
The query below will show you the sites results on the console.
select * from sites;
You would first have to create the sites, the first column increments up so that number must be unique on each insert, the second column is the name, then description, tenantID default is 8, then you can use the unix_timestamp() function to enter the current time and you use N for the deleted column like in the example below:
insert into sites values(2,'site2','Description2',8,unix_timestamp(),'n');
The subnets are in the reporter.networks table and each row maps back to a siteID, so once all the sites are created, you can then add the network like below, the first column has to be unique, and the last column has to match the siteID from above.
insert into networks values (5,'network5','126.96.36.199/24',2);
You can then verify the site has the proper networks by looking at the Admin->Sites page: