Merge pull request #1110 from DavisHenckel/FAQ_Docs

FAQ/How to Create an Empty Excel File.md

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+# Create an Empty Excel File
+Use an empty string to export to an excel file.
+```powershell
+#Build an Excel file named: "file.xlsx" containing a worksheet: "MyWorksheet"
+"" | Export-Excel -Path "C:\Test\file.xlsx" -WorksheetName "MyWorksheet" 
+```

FAQ/How to Read an Existing Excel File.md

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+# How to Read an Existing Excel File
+## Enumerate the Excel File Contents
+```powershell
+#Load the Excel file into a PSCustomObject
+$ExcelFile = Import-Excel "C:\Test\file.xlsx" -WorksheetName "Sheet1" 
+```
+
+## Visual of Data Structure
+The File C:\Test\file.xlsx contains  
+![ExcelFileContents](/images/FAQ_Images/ExcelFileContents.png)
+
+After loading this data into ```$ExcelFile``` the data is stored like:  
+![ExcelFileDebugImg](/images/FAQ_Images/ExcelFileDebugImg.jpg)
+
+## Other Common Operations
+
+### Load a Column
+```powershell
+$SpecificColumn = $ExcelFile."anotherHeader" #loads column with the header "anotherHeader" -- data stored in an array
+```
+
+### Load a Row
+```powershell
+$SpecificRow = $ExcelFile[1] #Loads row at index 1. Index 1 is the first row instead of 0. 
+```
+
+### Map Contents to Hashtable to Interpret Data
+Sometimes mapping to a Hashtable is more convenient to have access to common Hashtable operations. Enumerate a Hashtable with the row's data by:
+```powershell
+$HashTable = @{}
+$SpecificRow= $ExcelFile[2]
+$SpecificRow.psobject.properties | ForEach-Object { 
+    $HashTable[$_.Name] = $_.Value
+}
+```
+To then iterate through the enumerated Hashtable:
+```powershell
+ForEach ($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
+}
+```

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

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+# Write to an Existing Excel File
+### Enumerate the Excel File
+The cmdlets ```Open-ExcelPackage``` and ```Close-ExcelPackage``` allow for direct modification to Excel file contents.
+```powershell
+$ExcelPkg = Open-ExcelPackage -Path  "C:\Test\file.xlsx"
+```
+Contents of file.xlsx:  
+![ExcelFileContents](/images/FAQ_Images/ExcelFileContents.png)
+### Enumerate the Worksheet to View or Modify the Data
+```powershell
+$WorkSheet = $ExcelPkg.Workbook.Worksheets["sheet1"].Cells #open excel worksheet cells from worksheet "sheet1"
+```
+Visual of data structure:  
+![DataStructureExcelPkg](/images/FAQ_Images/DataStructureExcelPkg.png)  
+A1 contains "someHeader", A2 contains "data1" etc.
+### Modify a Specific Value in a File 
+Values can be accessed by row, column. Similar to a 2D array.
+```powershell
+$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)  
+### Load Value at Specific Index
+```powershell
+$ValueAtIndex = $WorkSheet[2,1].Value #Loads the value at row 2, column A
+```
+```$ValueAtIndex``` now contains: ![ValueAtIndexData](/images/FAQ_Images/ValueAtIndexData.png)  
+### Save File After Modifying
+The changes will not display in the Excel file until Close-ExcelPackage is called.  
+```powershell
+Close-ExcelPackage $ExcelPkg #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.
+