I modified your code to make it more useful.
DECLARE @s-2 NVARCHAR(MAX)
DECLARE @result INT
DECLARE @count_me NVARCHAR(MAX)
/*
The string to be searched.
*/
SET @s-2 = '1101001001110101'
/*
The character to be counted.
*/
SET @count_me = '00'
/*
Replace the character to be counted with empty string,
and subtract the lengths.
*/
SET @result = (LEN(@s) - LEN(REPLACE(@s,@count_me,'')) )/LEN(@count_me)
/*
Do something with the result
*/
PRINT @result