Pass c# parameter to SqlQuery

Question

    string SQLstr = @"
 DISTINCT * FROM(
 SELECT A.DOCNUMBR, A.CURNCYID, C.CRNCYSYM, C.CRNCYDSC, A.DOCDATE, B.CUSTNAME, A.TRXDSCRN, A.CHEKNMBR, CASE WHEN a.CURNCYID = (SELECT TOP 1 FUNLCURR   FROM   dbo.MC40000) THEN A.ORTRXAMT  ELSE(SELECT  ISNULL(SUM(ORDBTAMT), 0) FROM    dbo.RM10101 WHERE   DOCNUMBR = A.DOCNUMBR AND RMDTYPAL = 9)  END AS CURTRXAM,
  ISNULL((SELECT CMPNYNAM FROM DYNAMICS..SY01500 WHERE INTERID = 'TWO'), '') AS COMPANYNAME
 FROM dbo.RM10201 AS A
INNER JOIN RM00101 AS B ON A.CUSTNMBR = B.CUSTNMBR
 INNER JOIN DYNAMICS..MC40200 AS C ON C.CURNCYID = A.CURNCYID
 WHERE DOCNUMBR LIKE 'ParameterHere'

 UNION ALL

 SELECT A.DOCNUMBR,A.CURNCYID,C.CRNCYSYM,C.CRNCYDSC,A.DOCDATE,B.CUSTNAME,A.TRXDSCRN,A.CHEKNMBR,CASE WHEN a.CURNCYID = (SELECT TOP 1 FUNLCURR FROM   dbo.MC40000 ) THEN A.ORTRXAMT ELSE (SELECT  ISNULL(SUM(ORDBTAMT), 0) FROM    dbo.RM10101 WHERE   DOCNUMBR = A.DOCNUMBR AND RMDTYPAL = 9 )  END AS CURTRXAM ,
  ISNULL((SELECT CMPNYNAM FROM DYNAMICS..SY01500 WHERE INTERID = 'TWO') ,'') AS COMPANYNAME
 FROM dbo.RM20101 AS A
INNER JOIN RM00101 AS B ON A.CUSTNMBR = B.CUSTNMBR
 INNER JOIN DYNAMICS..MC40200 AS C ON C.CURNCYID = A.CURNCYID
 WHERE DOCNUMBR = 'ParameterHere'
 ) AS MAIN ";



    SqlDataAdapter da = new SqlDataAdapter(SQLstr, obj.SQLConn);
    DataSet ds = new DataSet();
    da.SelectCommand.CommandTimeout = 99999999;
    da.Fill(ds);

In the SQLstr how to pass parameter CshRcptDocNum to the query: 

string CshRcptDocNum = RmCashRept.RmCashReceipts.DocumentNumber.ToString().Trim();

 I want to replace the ParameterHere in the query with CshRcptDocNum string ?!