[Konstantinos]

Since you include ZCMD, it'd be good to actually use it instead of strcmp.
You don't need strcat and an array to store the text because it's small so it can be done directly in ShowPlayerDialog.

pawn Код:

#define FILTERSCRIPT

#include <a_samp>
#include <zcmd>

#define DIALOG_HELP 100

CMD:server(playerid, params[])
{
    ShowPlayerDialog(playerid, DIALOG_HELP, DIALOG_STYLE_MSGBOX, "Server", "[X] San Fierro COps N Robbers.\nServer Made by FrakyX.\nServer Forums www.xcnr.freeforums.org.", "Ok", "Cancel");
    return 1;
}

Last, nice way to advertise your forum.. you could use some other name (that doesn't direct to a server's forum).