A good way to get familiar with TKnwIRR is to open the IRR Demo project included with this distribution. Usage and tips are documented as comments in the Main.pas file.
If want to jump right in, drop a TKnwIRR component on a form. Connect the component to a data source using the DataSource property. Connect TMaxIRR to the cash flow data in a data set connected to the data source using the DataDateField and DataCashField properties. Run the project, calling the component's Execute method which will return the annualized IRR as a double type that you can convert to a percentage value or string. Nine times out of 10, that's all there is to it.