Anyone here knows slf4j ????

can anyone here brief me on SLF4J.
I did see http://www.slf4j.org/manual.html

But honestly i find the api highly undocumented. (even googling like hell didnt help)

Topics i need help in:
- Custom Pattern logging (like in log4j)
- levelling / threshold levels / hierarchy (i understand that all of these may not be supported by slf4j)
- loggin to Files
- logging to files filtered by levels