When one sets up a transaction, the input of the transaction needs to have a script with a signature to show that you can spend those coins. Which fields of the previous and current transactions need to be concatenated into a message and signed to generate a proper signature? Can someone provide some examples?
The transaction can then be sent using either of the following:
Here and in the following articles I explain how to build and sign a Bitcoin transaction from scratch. There are also C code examples attached: