How to find out locking and blocking in sql server using t-sql?

SELECT  r.session_id,
            s.host_name,
            s.login_name,
            r.start_time,
            r.sql_handle,
            r.blocking_session_id,
            SUM(r.reads) AS totalReads,
            SUM(r.writes) AS totalWrites,
            SUM(r.cpu_time) AS totalCPU,
            SUM(tsu.user_objects_alloc_page_count + tsu.internal_objects_alloc_page_count) AS writes_in_tempdb
    FROM    sys.dm_exec_requests r
    JOIN    sys.dm_exec_sessions s ON s.session_id = r.session_id
    JOIN    sys.dm_db_task_space_usage tsu ON s.session_id = tsu.session_id and r.request_id = tsu.request_id
    WHERE   r.status IN ('running', 'runnable', 'suspended')
      and r.blocking_session_id <> 0
    GROUP BY    r.session_id,
                s.host_name,
                s.login_name,
                r.start_time,
                r.sql_handle,
                r.blocking_session_id