Switching from ASP.Net to SAP web technologies

Hello guys i'm working now as an asp.net developer and i wants to switch to SAP i have searched a lot about SAP technologies and i found that there is BSP and web dynpro with abap and also web dynbro in java, i don't know where to start if i wants to learn SAP web technologies any help would be appreciated and do i have to learn all of the above or only one technology would be enough, currently i have a good knowledge in ASP.Net, SQL Server, HTML, CSS, JavaScript, JQuery, AJAX thanx in advance