[0ne]

Indent the code, and add do on commandtext like this:

Код:

public OnPlayerCommandText(playerid, cmdtext[])
{
 if (strcmp("/geber", cmdtext, true, 10) == 0)
 {
  SetPlayerHealth(playerid,0);
    return 1;
 }
return 0;
}

for the 4th warning, you didn't use the command anywhere.