how can i create an item for each supplier ??
Your question is not clear. What kind of item are you referring to?
for ex: if i have a supplier named AAA and i do buy from their company a laptop for 5$ and a mouse for 1$
and i do buy different products like paper for 2$ from different company
how can i create a list for each supplier containing their products
You cannot. Suppliers and inventory items are created individually in separate tags. Once an inventory item is created, it can be purchases from any supplier who sells it and sold to any customer who wants to buy it.