How can i import supplier invoices. I am new to this and need help to keep track of purchases. Do I need to input manually. If so How do I do this?

You would have to shop in the intuit app store to find an add on to import supplier invoicing as Bills. Even if created by supplier in Quickbooks there is not a Quickbooks import feature built in.

Otherwise you enter them manually just like entering everything else - from the "+" entry menus. It is tiny and far from obvious as it is not front and center or significant in size (it once was) but click on "+" and in the column labeled Vendor or Supplier choose the option Enter or Create Bill's. That is where you enter the supplier invoices. Later when you are ready to pay access the same menus and choose Pay Bill's to create a cheque or record a digital payment. Do not bypass bill pay and only create a cheque as the bill will remain unpaid and you will have doubled expenses (accrual based)