Complete first version of ExistingExcelFile FAQ

Added loading a row/col, then mapping to HashTable

FAQ/How to Read an Existing Excel File.md

@@ -12,3 +12,29 @@ The File C:\Test\file.xlsx contains
 
 After Loading this data into ```$ExcelFile``` the data is stored like:  
 ![ExcelFileDebugImg](/images/FAQ_Images/ExcelFileDebugImg.jpg)
+
+## Other Common Operations
+
+### Load a Column
+```powershell
+$SpecificColumn = $ExcelFile."anotherHeader" #loads column with the header "another header" store into an array
+```
+
+### Load a Row
+```powershell
+$SpecificRow = $ExcelFile[1] #Loads row at index 1. Index 1 is the first row instead of 0. 
+```
+
+### Map Contents to HashTable to interpret data
+Sometimes mapping to a HashTable is more convenient to have access to common Hashtable operations. Enumerate a HashTable with the Row data properties by:
+```powershell
+$HashTable = @{}
+$SpecificRow= $ExcelFile[2]
+$SpecificRow.psobject.properties | ForEach-Object {$HashTable[$_.Name] = $_.Value}
+```
+To then iterate through the enumerated hash...
+```powershell
+ForEach ($Key in ($HashTable.GetEnumerator()) | Where-Object {$_.Value -eq "x"}){ #Only grabs a key where the value is "x"
+    #values accessible with $Key.Name or $Key.Value
+}
+```