item.wil is for all items as in viewable in bag (f9)
dnitem is for items that go onto the floor
Stateitem is for all items that are usable by players on (f10)
with that said get the image you require and find a slot in all 3 of the above mentioned files that is empty then import that item to it , remember the number then go to sql and make an item name and then use the item number from HH8 in imageindex the other numbers you can see by yourself by looking at shape of other items , then u need to know the stdmode these are 4 or 5 for one and 2 handed weapons , 10 and 11 for male and female armour, 22 and 23 for rings so on and so forth but if you LOOK at the sql DB you will see what is required. thats it for items
now mobs are different
you will either need a program to tell you the imgindex or use the graphics folder in the client with single wil mobs.
my opinion the graphics folder is the way to go
so go to your client folder
make a folder called Graphics
inside that folder make a folder called Monster
inside that make a mon.wil using hh8 editor and call it 2000 next 2001,2002 and so on all must be single monster wils other wise it wont work.
then in sql Monster table add the mob using your information making sure that the monsters imgindex is 2000, 2001, 2002 and so on for each individual mon.wil that you have created.
hope that helps as i cba to explain it any better :P
edit:- added a 22 to bracelets.