Client indexes range from 1 - MaxPlayers, and each client's index reflects what server slot he's connected to.
So if you want the client connected to slot 1, then the index would be 1. 2 is 2, 3 is 3, etc.
You are also mixing aspects of the "old" and "new" Sourcepawn syntaxes. You should put "void" inbetween "public" and "OnPluginStart", and replace this:
PHP Code:
public Action OnRoundStart(Handle:event, const String:name[], bool:dontBroadcast){
with this:
PHP Code:
public Action OnRoundStart(Handle event, const char[] name, bool dontBroadcast){
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