Purging Log File

How can I reset a log file for a database that is active. The file is 8
gigs. I want to restrict its growth to 50 MB and purge the contents.
How can I do this.General info on file shrinking as well as link to shrinking log file size:
http://www.karaszi.com/sqlserver/info_dont_shrink.asp
Tibor Karaszi, SQL Server MVP
http://www.karaszi.com/sqlserver/default.asp
"Ross B." <ross@.__computaught__.com> wrote in message
news:u%2382JFQDEHA.1600@.tk2msftngp13.phx.gbl...
> How can I reset a log file for a database that is active. The file is 8
> gigs. I want to restrict its growth to 50 MB and purge the contents.
> How can I do this.
>