Newby Help needed

Hi all, i'm newby to postgresql: really great product.

I'm trying to understand exactly how to set up WAL  archiving.
I read the doc ( by the way i'm running postgresql-8.1.11 ): i need some
explanation on how are created and recycled theWAL bacause i cannot
understand, for example, how is filled-up the dir pg_xlog/archive-status.

I noticed that sometimes the same file is present in pg_xlog dir and
also in archive-status dir with the extension .ready. Then, after some
time ( i cannot understand how long, and wehre this parameter, if any,
is written ) it disappear from only archive-status directory...

Some one can help in understanding these ??

Many thanks in advance to any one will post an answer..

--Andrea