I wanna build a simple social network use python. Just like twitter but smaller than twitter.I just wanna make a few features like follow,BE followed,view others profile,etc.
My question is that i should use web.py or Tornado?
BTW, is there any tutorial about Tornado? I feel it hard to understand when i read the documenations on the offical.
(Oops,my english is week. :P )
You might consider using Pinax.  When I used it, it had the self-concept of 'django with an opinion.'  I'm not sure where it's at now, but my experience was that it was best suited for exactly what you want to do.  One of the base projects is actually a fully functional social network site.  You could then customize from there.
Choose web.py or Tornado