You must first deposit money into your investment account to fund any investment purchases. In Quicken, this transaction is recorded as a transfer of cash into the investment account.
You can either record the transfer as a lump sum to establish a cash balance, or handle the transfers incrementally as you enter each Buy transaction.
It is also possible to fund an investment account by transferring shares from another investment account. These shares can then be sold to raise cash to fund new purchases.
Recording a transaction in Quicken does not execute a real-world trade, transfer, or other transaction. Contact your broker to execute trades or transfers, and then manually record the transactions in Quicken—better yet, download them directly from your participating financial institution.