Complete Majority of Write to ExistingExcelFile md

FAQ/How to Write to an Existing Excel File.md

@@ -16,4 +16,16 @@ Modify a specific value by accessing row/col like a 2D Array:
 ```powershell
 $WorkSheet[1,4].Value = "New Column Header" #Starts at index 1 not 0
 ```
+Contents of file.xlsx after modifying:  
+![ExcelFileContentsPostAdd](/images/FAQ_Images/ExcelFileContentsPostAdd.png)
+Can also load a value at a specific index:
+```powershell
+$ValueAtIndex = $WorkSheet[2,1].Value #Loads the value at row 2, column A
+```
+### Save File After Modifying
+The changes will not display in the Excel file until Close-ExcelPackage is called.  
+```powershell
+Close-ExcelPackage $ExcelPkgFile #close and save changes made to the Excel file.
+```
+**Note**: If the file is currently in use, Close-ExcelPackage will return an error and will not save the information.