Thank you for your enquiry, information regarding ticketing for Big Bash League games can be found on Ticketmaster's website - Tickets for Concerts, Sport, Arts, Theatre, Family, Events, more. Official Ticketmaster site 

Children aged 3 years and under are permitted free into the ground providing they do not occupy a seat. Juniors aged 3 years and under must sit on a supervising adult's lap for free entry and do not require a ticket for entry.