is your existing cover split or damaged mate ?
to be honest they are only like £6 or sumthing so its easy to replace them.
firstly unplug the breather
All you do is take the two bolts of the top of the rocker cover think they are 10mm or 12mm
then lift the rocker cover of
the plate will be left on top of the valves with the two spaces on the holes
if its ont then it wil be stuck inside the rocker cover, all you do is pull it out then sit it on the valves and put the two spacers over the holes then put your new rocker cover on.
Hope this helps you