UnderStand Hacker Attack and site secuirity

hi every body

i want to understand if any hacker attack to my site.

1-how can i understand the attacker ip and how(which way eg Injection or ..) he attack me?

2-how can i log my event of site and any thing that user do in site?

generally i want to control my site because i m going to build a goverment site that geek user attack it .if any subject help me give it to me(just about site not server).