There is a Report button at the top right of every post. To report spammers, click it , select the reason for the report from the dropdown menu and send. The offender will be dealt with accordingly. 
Three tips.
1: Never reply to a spam post. Just report it and move on.
2:There is no need to make multiple reports on the same offender.
3: Do not use the Report button for frivolous reasons, unless you want to join the spammers in Forum Purgatory
