The reason for your error is that you are using the Excel Selection, instead of the Word one. Inside your With you should use .Selection, HOWEVER the Word Selection does not belong to the Document so you should be using With WordApp.

Although it is unlikely to go wrong, the way you open your Document with GetObject is not guaranteed to use the instance of Word you have created with the CreateObject. As you won't be using the WordDoc object after you make the change above I would suggest doing it this way

[VBA] Set WordApp = CreateObject("Word.Application")
With WordApp
.Documents.Open "C:\Documents and Settings\sb008078\Desktop\AUTOMATION\Automating word\automation.doc"
.Visible = True
.WindowState = wdWindowStateMaximize
.Selection.GoTo What:=wdGoToBookmark, Name:="bk1"
.Selection.Find.ClearFormatting
With .Selection.Find
.text = ""
.Replacement.text = ""
.Forward = True
.Wrap = wdFindContinue
.Format = False
.MatchCase = False
.MatchWholeWord = False
.MatchWildcards = False
.MatchSoundsLike = False
.MatchAllWordForms = False
End With
While Rindex < 11
Rindex = Rindex + 1
Cindex = 0
.Selection.MoveDown Unit:=wdLine
While Cindex < 11
.Selection.TypeText text:=Worksheets("Sheet1").Cells(Rindex, Cindex).Value
.Selection.MoveRight Unit:=wdCell
Wend
Wend
End With[/VBA]

As a side note - if you enclose your code in VBA .. /VBA tags it is much easier to read.

I don't have your document so can't be sure what you have, but I note as I write this that you don't execute the Find, so what is it doing? I would also suggest that you try and avoid using the Selection object at all. If you have a reference to your table you can use either the Cell method or the Rows and Columns properties.