Move from Support development to Core development

Question

Hello All,

 

I am working as Team lead in developement support role. I am in development support since 4 years but now I would like to move to core developement side. I am working in ASP.Net and SQL server. Can anyone suggest me right way to optimize my skill and how I can gain confidence on my skill? I am learning new things using tutorials but it is not helpful to me at all as currently there are very advanced technologies available in the market.