This will show you your ads account. You have to select manage pages from the drop down on the upper left of your screen. Check in the screenshot
Now select the page(on the left hand side) for which you want to create one.
When you click on the create post this box will open up in your window
Now put the information accordingly.
Put the link for which you want to create post. After that put text which you want to use then select one call to action out of these five. Headline for your link, Display link and description put all these accordingly. You can also upload image of your choice or Facebook will fetch the image from your link (If link have any image).
You can use this post for an ad or you can publish it organically on your page. As we are creating this to post organically select second option and click on create post.
I have created one to show an example. After clicking on create post your all posts will shows up and the one that is unpublished there is a blue/white sign on that post. Check in screenshot:
After reviewing you post how it looks like you can click on publish now. Hang on, this is not done, after clicking on publish now you have to click on the upload changes.