[ask] about configuration mikrotik RouterOS

hello friend
i have problem with my configuration routerOS Mikrotik
this my topologi network

 
                192.10.11.1                               192.10.11.2
                   Router A                               router B
                             \                           /
                                \                      / 
                                   \                 /
              router F-----------------gateway ISP  -----------------router E
            192.10.11.6               192.10.11.254                192.10.11.5
                                  /                \
                                /                     \
                              /                         \
                   192.10.11.3                          192.10.11.4
                     Router C                            router D

[illustration/explanation]
all router (Router a-f) connect to gateway with wireless link 3.2 mbps
every router connect to gateway 192.10.11.254
every router have internasional bandwidth 512 kbps and lokal bandwidth 2 mbps
example :

.......router A
...........|
...........|
get bandwidth from router b-f 
but now, he have bw from isp n will increase the bandwidth from router b-f
...........|
...........|
.....ISP gateway for router A-f-----------router f
.....|......|.........|.......|
router b....|.........|.......|
...........router c...|.......|
......................|.......|
..................router d ...|
...........................router e

or u can see this picture

or klik link this
http://i148.photobucket.com/albums/s21/sherayusuf/asdasdasd.gif

[question]
how to setting router a to get bandwidth from router b-f ??(i will make load balanced on router a from bandwidth router b-f)

sorri if my engglis is bad
im indonesian

thnk before to all