i knew that the main battle is SERVER BATTLE but i didnt know how can we participate in that SERVER  BATTLE.

can someone share some ways and what is the benefits when we attend it?

In server verse server battle.  It happens every Wensday, Saturday, and Sunday.  It happens 3 times during those days.  When it opens(There will be a message on screen).  You click the button on the right with 2 crossed swords, and click participate in Server Battle.  It will then put you in qeue and you will be placed in within 5 minutes.

ahhh thats is it...tQ, looks like i miss that 2crossed swords. btw what will we get from  participatng in it? some items or.....?

In SvS, you are awarded SvS points.  These points can be used to buy costumes that can be used to replace cash-shop costumes.  You can use these costumes to change your appearance, but you cannot use skills while you are in that appearance.  You can also equip them for a defense, HP, and MP buff along with several more reinforcement slots.  You can buy a Xeon Removal item that removes a xeon from one of your equipment.  You can also buy exp scrolls.

With SvS if you do well you can earn on average 500k exp.

now all of us knows that SvS is worth to attend. there will be much to gain, haha lets have a good SvS to raise this MMORPG's Fun.