God someone please please help me with INVENTORIES

This area of the syllabus is absolutely driving me insane.

My questions is:

1st step:
Information is taken out of the books of prime entry and put into ledger accounts

2nd step:
Balance the accounts off and transfer balancing figures, asset and liabilities to balance sheet and the income and expenses to the income and expenses trading account “also a T account”

After this I get stuck, ive explored so many variations that ive got millions of questions buzzing in my head.

1. Where does the double entry into the Inventories account come from? I/S?
2. Is the Income statement the exact same thing as the Income statement journal? Just rearranged in a different way to calculate cost of sales?
3. Must you have to do the journal to work out the closing inventory in order for you to get a closing inventory figure to transfer out to the balance sheet?

If someone would be kind enough to explain or even better do a word document of an example of simple transaction initiating from the first step e.g books of prime entry through to the Inventory account, I/S and balance sheet so that I can see how it is working?

Thanks in advance any help appreciated