too late for this reply but either way... ill reply
if you've read some guides, chances are you could create your very first 32-bit constant write code, its always good to start on creating item codes for pokemon, Pokemon games has a very established coding system, Hex values are often repeated or recycled in every generations, basically in order for you to find or create a code, you need a software, and a rom, what i use before was no$gba and emucheat or emuhaste but now i use desmume. basically the goal is to isolate a particular code offset by using a particular hex marker, then make a series of changes to your marker like lets say a pokeball is A that is slot 1, do ram search with and the software will give you all offsets that has a value of A, then switch it up like let say your Great Ball is B and is on slot 2 put it on your slot 1, do a ram search again then from the pool of offset that has A value on, will be reduced to all values that has B on it. do process several times and once you have at least 1-3 offsets, thats the time to look closer. take note of those offsets then start trying them. one of these values would you item modifier for slot1 and normally for items its in array so +2 or+ 4 in the offset value would render the quantity of the item or the offset value for item slot 2