Transact SQL :: Identify Blocking Process

Imagine I set a begin transaction on table a and updating a row and not committed and not roll backed--first connection

From second connection I am selecting same table (obviously it wait until first connection commits/rollback based on my transaction level: my isolation level is read committed).

1. How do I know second connection is to waiting to first connection to complete.
2. If I want to select rows that are not locked by update process how do i need to do(ex:row 1,2,3,4 and 1 is locked by update process(exclusive lock) and i want to leave that and i need to select 2,3,4 records).