To store information in a hash table, you would use the /hadd command.

To retrieve information from a hash table, you get it, which is why the identifier for that is $hget

I didn't write this up for you, since you said you wanted to learn how to do it yourself. As I said earlier, if you want to use hash tables (and I would recommend it for this), read up on hash tables in the help file /help hash table and maybe check out a tutorial (I think there's a couple in the tutorial section of mIRC.net )