You appear to have made up some of your own syntax and in any case it would not work when you press the enter key. It is not clear whether you want some or all of the text moved. The following will facilitate both. Note the Cell.Next command will move to the next row if the selected cell is the last in the row, so the code checks to see if the cell is the last in the row, so that Next only works in the same row.
Code:
Sub MoveSomeTextInCell()
'Moves selected text within a cell
Dim oTable As Table
Dim oCell As Cell
Dim oRng As Range
If Selection.Information(wdWithInTable) = True Then
If Len(Selection.Range) = 0 Then
MsgBox "Nothing selected", vbCritical
Exit Sub
End If
Set oRng = Selection.Range
Set oTable = oRng.Tables(1)
Set oCell = oRng.Cells(1)
If oCell.RowIndex = oCell.Next.RowIndex Then ' Check if next cell exists
oCell.Next.Range.InsertBefore oRng.Text
oRng.Text = ""
Else
MsgBox "Cannot move text to the right, as there is no adjacent cell.", vbCritical
End If
Else
MsgBox "Select a cell within a table.", vbCritical
End If
End Sub
Sub MoveAllTextInCell()
'moves all of selected cell contents
Dim oTable As Table
Dim oCell As Cell
Dim oRng As Range
If Selection.Information(wdWithInTable) = True Then
Set oTable = Selection.Tables(1)
Set oCell = Selection.Cells(1)
Set oRng = oCell.Range
oRng.End = oRng.End - 1
If oCell.RowIndex = oCell.Next.RowIndex Then
oCell.Next.Range.InsertBefore oRng.Text
oRng.Text = ""
Else
MsgBox "Cannot move text to the right, as there is no adjacent cell.", vbCritical
End If
Else
MsgBox "Select a cell within a table.", vbCritical
End If
End Sub