First of all, when installing Tails, make sure persistent
storage is enabled. When starting Tails unlock persistent
storage with your password.

After that open Apps/System Tools/Console

Once open type:

$ cd Persistent
$ wget https://github.com/Ch1ffr3punk/oc/releases/download/v0.1.0/ocmix-client-linux-amd64
$ wget https://github.com/Ch1ffr3punk/oc/releases/download/v0.1.0/oc.zip
$ mv ocmix-client-linux-amd64 ocmix
$ chmod 700 ocmix
$ 7z x oc.zip
$ chmod 700 oc
$ cd oc
$ chmod * 600
$ cd ..
$ rm oc.zip

Inbetween you can always do $ ls -la to see the directory content.

After that you can run ocmix with ./ocmix -i to update the oc folder
and then do an ./ocmix -p to see the status of the mix nodes, prior
posting your article.

To write your Usenet article:

$ nano msg.txt

which should look like this:

To: ugf7olo27n5nq2jr6yoai2j5jo24ogx6yemjaozsgxg3byfpcpwdg7id.onion:8088

Subject: Test
Newsgroups: alt.test.test

Hello world.

To write your email message:

To: zrfezqe7i47fsxes5ingarvpz4dgaq3ttszkos7kfzm5liwpdpq322qd.onion:8088

To: Bob <bob@example.org>
Subject: Hello Bob

Hi,

have a nice day.

Regards
Alice

Direct messsage to an Onion Courier endpoint server:

To: yeffqiea4xtcu6woyab6z6bz4oehisfuzgtmk4e277bydq25p7nha7ad.onion:8088

Hi Bob,

see you Sunday at 10:00 AM.

Regards
Alice

In nano press CTRL-o to save your article and then press CTRL-x to quit nano.

You don't have to add the three MIME headers or Date and Message-ID headers,
because this is done automatically.

To send your article:

$ ./ocmix node1,nodes2,node3...(up to 5) < msg.txt

That's all.