BasicAccounting.pdf is the Manual for the course "Basic Accounting for Business People"
TheFlowOfMoney.pdf also called "Money Pipes", is a diagram outlining the flow of money as a pipe network for a typical business.
MoneyFlow_Calc01.ods is a LibreOffice Calc Spreadsheet to play with the Credit & Debit idea.
T-Accounts.ods is a LibreOffice Calc Spreadsheet to play around with T-Acounts.
https://gnucash.org/download.phtml is the download page for GnuCash.