this ?
if ( BaseLevel != 255 || JobLevel != 120 ){ next; mes @name$; mes " Your Base level must be 255 and your Job level must be 120"; close;}
add that before
next;
mes @name$;
mes "Please choose a job.";
switch(select("Lord Knight","High Priest","High Wizard","Whitesmith","Sniper","Assassin Cross","Paladin","Champion","Professor","Stalker","Creator","Clown")){