Keep in mind there is a problem with filters in 5.x to be fixed in the next release 5.7 ;-( (at least using the gui)
(see
http://forum.mikrotik.com/viewtopic.php?f=14&t=54616)
You really have only to setup the instance and peer, I found that depending on what OS I am peering with, I usually select the interface on the peer as opposed to leaving it unassigned...
an example of some filters on the outbound.. for example to make sure you don't inadvertently advertise something you don't mean to...
/routing filter
(be sure to use all combination of routes and their aggregates if appropriate)
add action=accept chain=peer1-out comment="" disabled=no invert-match=no prefix=1.1.1.0/22
add action=accept chain=peer1-out comment="" disabled=no invert-match=no prefix=2.2.2.0/22
add action=discard chain=peer1-out comment="" disabled=no invert-match=no
an example of a filter on the inbound to keep only the shortest path routes (1 or 2 as-paths)...
add action=discard bgp-as-path-length=3-32 chain=in-short-only comment="" disabled=no invert-match=no protocol=bgp
an example of a filter on the outbound to pad with additional as-path...
add action=passthrough chain=peer1-out comment="Prepend on peer1" disabled=no invert-match=no set-bgp-prepend=1