How do I contract out products from my corps into my own stock?

I've been told I can do this but not how lol

In your country's state-owned corporations or in your CEO, click on the corporation's name, then look on the corporation's page where it says "Contracts" and "Review corporation contracts."

There are two options: a) Contract all production to the country/CEO or b) Propose a new contract to countries or their corporations.

I hope this helps; I'm using Google Translate:

Best regards!

Sorry, I got confused.

On your CEO's main page at the top, there are three options: "Finance, Trade and Corporations." Click on "Trade." A submenu with several options will appear. Choose "Trade with Own Corporations." The assets your CEO owns will appear.

Choose Gasoline, for example, and click on "Sell." A list of your CEO's corporations will appear where you can sell the asset.

It is also possible to do it for many corporations much faster.

click on the corporations page.
there are many tabs at the top.

several tabs are about contracts and contracting products to your country.
please look into these tabs, you will quickly find how to set up contracts to as many corporations as you need.