>I want to do something as:
>
>If thisDatetime > datetime()
>do event01_start
>
>---------------------------------------------------
>
>How can I store value to thisDatetime ?
>
>Can I simply use "01/01/2009" 15:35" ?
>
>system is set to 24hs

Try to use datetime() function with parameters for date and time (see in Help). For date() funciton it's
date(1999,10,1) (year, month, day).

datetime(year, month, day, hour, minute, second)