The best thing to start with is probably "sp_who" or "sp_who2". That will at least show you what processes are running in SQL and whether there is any blocking going on. There are ways to find out what statement a particular process is working on.
DBCC INPUTBUFFER (spid) -- replace spid with the actual numeric value
or
DECLARE @handle binary(20)
SELECT @handle = sql_handle FROM master..sysprocesses
WHERE spid = SPID -- replace with actual numeric value
SELECT [text] FROM ::fn_get_sql(@handle)