Download the bf2 plugin (or any other ranking plugin) and have a look.
Code:
format(HUD, 80, "[BF2]Kills: %d/%d Badges: %d Rank: %s ",totalkills[id],nextrank[id],numofbadges[id],RANKS[g_PlayerRank[id]])
message_begin(MSG_ONE_UNRELIABLE, gmsgStatusText, {0,0,0}, id)
write_byte(0)
write_string(HUD)
message_end()
Thats the code for the Hud message (thing down the bottom) and its called on every curweapon event.
If you want to do kills in a round you could use the csstats module (
get_user_rstats), or if you just want total number of kills you can also use the csstats (look it up yourself).
For total kills you have to rememebr that csstats will auto reset itself if the file gets too big. If you don't want this to happen you will need to log the kills yourself.
Register the message DeathMsg and count users kills using that.
Xp mod tutorial. - By Xuntric/Pm, definately worth a read if you havn't already..