Assuming you know how to open up your vba editor so I'll skip that part.
Create a subroutine and call it whatever you want, we'll call it test for a visual explanation.
Then create a variable to attach to the sheet that you want, lets say the first sheet.
Then you can access the cells of the worksheet through the Cells(row, column) attribute.
To open a file for reading use the open keyword.
Use line input to get read the file line by line and once you encounter the word that you are looking for start recording the contents of the file into the worksheet. The text that is in red is that which will depend on you. For the most part, this is the basic logic that you need for the code.
Private Sub test()
Dim theSheet As Worksheet
Dim iFile As Integer
Dim sLine As String
Dim bRecord As Boolean
Dim lRowCntr As Long
'set theSheet equal to the sheet
Set theSheet = Application.ActiveWorkbook.Sheets(1)
'get the next free file handle
iFile = FreeFile
lRowCntr = 1
'open the file
Open "yourfile.txt" For Input As #iFile
While Not EOF(iFile)
Line Input #iFile, sLine
If Trim(sLine) = "your phrase" Then bRecord = True
If bRecord Then
theSheet.Cells(lRowCntr, 1) = Trim(sLine)
lRowCntr = lRowCntr + 1