Convert a Text to a Blob

I have 2 fields - 1) CreditCardNo (text 16) & 2) CreditCardNoBlob (Blob).

On Validate for CreditCardNo I want to push the text data to a blob - I understand you can use INSTREAM to do this - but I need help to get it right.

So far I have the following:

Definitions:

StreamInObj = DataType InStream
CreditCardNoProtect = BLOB
CreditCardNo = Text (16)

CreditCardNoProtect.CREATEINSTREAM(StreamInObj);

I am unsure what to do to get Credit Card No into the blob field.

Can someone show me what the code should be with an explanation on each line of how it actually works or what each line is doing. I looked at the example in the help text but not sure how much of it is relevant considering it seems to be writing messages.

Thanks
Kylea