If you are already done writing articles,  you have missed a part to get more visitors. you will also allow using meta keywords on HTML editor for every post let's begin. 

Copy the Meta keyword HTML

<meta name="keywords" content="">

First step

Go to HTML View

you will need to go to HTML View.. because the Meta Keyword is HTML type

paste meta keyword like this

2nd step

replace "your keyword" and then go back to Composite View that HTML tag does not show from composite view because it is HTML type.

Where to get Keyword for free?

Just use the Keyword Planner tool!!
Go to google ads (ads.google.com) > login to your google account.
you need to go through this step before going to the google keyword planner tool where you can get keyword for free

Follow video Instruction here: