Spider
To bowl in the Adult Nationals, you need to be over 18 before they start in that calendar year. Youth is for those under 18. Entries have closed for the current years nationals. To give you a heads up on requirements, you will need to have bowled at least 24 games (not including pre & post bowls) by 31 Dec of this year for the Adult Nationals. I don't know what the requirements are for Youth as i'm not involved there. Adult Nationals have 2 comps, Rachuig - Open (pronounced Rockway) and Walter De Veer - Graded. At present, WDV average is up to 169 for Mens & 159 for Womens though this may change. Your centre should have the nomination forms for all of these when they become available of visit tbaq.com.au and they will have them there.
PS What centre do you bowl at?