How to add inventory? the item has already been created, need to know how to add inventory once we receive (usually 4-8 items), like an inventory entry with several items

It's my pleasure to assist you in adding your inventory, userefaraj.

You can use the inventory tracking feature to help manage your inventory. To get started, let's turn it on. Here's how:

1. Go to the Gear icon at the top. 
2. Choose Account and Settings. 
3. In the left menu, click Sales. 
4. Go to the Product and services section and tap the pencil icon.
5. Turn on Show Product/Service column on sales forms.
6. Turn on both Track quantity and price/rate and Track inventory quantity on hand.
7. Tap Save, then Done. 

Once finish, when it's time for you to restock your inventory, you can enter reorder points when adding a new item. But if the existing item doesn't have the reorder points, you can edit those products to add them.

From there, track what you receive from your supplier. You can either do the following:

• Create a bill from the purchase order if you’ll pay your supplier later.
• Create a cheque or an expense from the purchase order if you paid your supplier on the spot.

After that, the system knows that you restocked in which it will increase the quantity on hand by the number of items you received. 

For more details about this process, check below articles: 

• Set up and track your inventory in QuickBooks Online
• Reorder inventory or supplies from suppliers

You may also find this helpful: Adjust inventory quantity on hand in QuickBooks Online.

Let me know if you have any other questions. I'll be around to help you out. Have a good one!