macro to locate locate text string and copy/paste offset range

Hello - fairly new to VBA code. I have a macro that opens multiple PDF files, converts to excel, and merges into one excel file. i then need to search for a particular text string, copy the entire row containing that string, plus the 11 rows below it, and paste into a new worksheet. I need to perform this task until I've captured all instances of the text string. The problem is that the text string does not always appear in the same column and is not a set number of rows from the last instance. I have the simple code to find the first instance, but struggling to loop through the remaining cells. i tried to use "findnext" but can't figure out the syntax. Can someone help? thanks

ActiveWorkbook.Worksheets("sheet1").Cells.Find(What:="PL Stg 1-2", after:=ActiveCell, LookIn:=xlFormulas, LookAt _
        :=xlPart, SearchOrder:=xlByRows, SearchDirection:=xlNext, MatchCase:= _
        False, SearchFormat:=False).Activate
        Rows(ActiveCell.Row).Select
        ActiveCell.Resize(12, 256).Select
        Selection.Copy
        Worksheets("sheet2").Activate
        ActiveCell.Offset(12, 0).Activate
        ActiveSheet.Paste