Who do I send money to if I want to create an OP_RETURN transaction I simply want to store one small string in the blockchain. That's it. I am reading here a step by step guide but there is little in terms of explanation beyond the code snippets. What I would like to know is if essentially the problem is this...

There are two parties: me and someone else. I need to somehow get that "someone else's" address, and can figure out the rest from there.

But the main problem is, I don't have any "someone else" I would like to send the money to (or even need to send money to). I simply want to place something in the blockchain.

How are people doing this in their tutorials? Who are they sending the money to? Are they just creating a "dummy transaction" against a "dummy address" of some sort, and then getting a refund of the money? That way it seems the data would still be in the blockchain, but then no money would be spent (other than a potential processing tax fee).

If so, how do I do that? Am I supposed to setup two bitcoin networks, and send data from one to the other? That is, create a transaction of sending money from one to the other? Or perhaps even easier (though not possible?), I can get two addresses from my bitcoin node, and then send money from one of those addresses to another. Is that possible?
Nothing prevents you to send bitcoins to one of your own addresses. I guess I'd just create a new address on my node with bitcoin-cli getnewaddress, and then create a transaction with 2 outputs :


one to the address I just got with my whole input amount (minus mining fees)
another to a "dummy" address (can be one you generated with the same method, you can't spend it anyway!) with OP_RETURN + [your_data], and of course 0 as amount


As for the exact way to do this, the post you linked too seems like it could work, but I never tested it myself. The idea is to create the transaction first with the createrawtransaction method from bitcoin-cli, and then modify a piece of the data with yours.

As I said I never did that, I highly suggest you try it out on testnet first, there are many things that could just go wrong.