Pokemon Silver (U) Event code help

Hey I was wondering on how to use the event codes?
I have the cheat codes on there but i didnt know how or when to use them...or maybe im at a wrong place?
I want to catch mew and it says on the cheat codes Event Codes 2 (L+R)
i tried pressing (L+R) but nothing happened...
Can someone please help? Thanks ^^

Check your PC.

Check box 1 slot 1 in bills pc.. you should have a mew there i think.

make sure there is nothing in slot 1

How did you get Cheats My soul silver doesn't have any.

http://cheats.gbatemp.net/Temp/