If you are planning to use only the first worksheet in the Excel file, but the worksheet name is unknown then the steps below should be completed:
1) Make sure that you are using 2.0 version of COZYROC SSIS+ and up, because this feature to reference sheet by index(:index) was first introduced in our 2.0 version
2) Right-Click on the Excel Source Plus component and select Properties. Look at the screenshot below:
3) On the Properties screen enter ':1' for property Worksheet. Look at the screenshot below:

If you would like to use always the second sheet when the name is unknown then you should enter ':2' for property Worksheet.
The index for the third sheet is 3 and etc..
If the specified sheet starts with the colon(:) symbol, then the Excel Source Plus component will treat the remaining definition as a sheet index.