Covert a String to a Byte[]

Hi there!
I have a string which is in the form a series of bits, e.g.:
01010111
And I want to covert this into the data type Byte and save it to a file.
How do I convert the string into a Byte in the most efficient possible way?
Thanks
Sydan

byte bytes = System.Text.Encoding.UTF8.GetBytes(“Hello Guys!”);
string str = System.Text.Encoding.UTF8.GetString(bytes);

**Another way to convert it is..**

			byte []bytesNew = System.Convert.FromBase64String ("Hello World!");
			string strNew = System.Convert.ToBase64String(bytesNew);

This sort of general programming question is usually found on StackOverflow, such as this: c# - How to convert a string of bits to byte array - Stack Overflow