Paragraph length

Can any one tell me which paramater us used to set teh max length in a paragraph. I need a seacrh page I am formatiing to look like those on google and other pages where teh text stops after a certain length. I thought it was rtrim but that does not work.

Example : blah blah blah bla..... more

Thanks fo rteh help cant find an answer anywhere been searching for a couple of days.