We have written about how to display recent sticky posts in WordPress, but we never covered how to make sticky posts which was our shortcoming because one of our users asked us this question. Making Sticky Posts in WordPress is really easy.
First you would need to login to your WP-Admin Panel, and open up the post page. Look towards the right hand sidebar where you will see a Publish box. Look at the (Visibility: Public) field and click edit. Check the box to make the post Sticky and publish it. If you want to make an older post sticky, follow the same steps and just click save.
Article from http://www.wpbeginner.com/