[PHP] Time in php problem....

[Ng Kok Chun]

hi... i need some help...

currently i doing web base programming ( econsultant )using php, apache and mysql as 
well... now i facing a problem which i need :
1) get time when consultant log on
2) get time when consultant log off
3) calculate how long for the specified consultant been log on to the web
4) accumulate all the time everyday
5) then multiple accumulate with working rate ( X ).
6.) finally output to web ( html form )

pls help !
thanks !