It is predicted that by 2019 , as much as 80% of the traffic on the Internet will be video.
If this is true,it is important to make use of videos now.
There are a number of video sites,but the largest is YouTube.  

When you’re making a YouTube video the thumbnail is very important .
Basically this is the first opportunity that people will see your video, so you need to make it quite appealing in order for them to click on it now as opposed to the thousands of others.

If you leave it to YouTube, the site will pick an image from your video which may not be very appealing.

What I do is a use a number of different sites to basically have a custom thumbnail.
I personally use pixabay ( http://www.pixabay.com ) where I find an appealing image .
These are free and of a very high quality.
I will download this image to my disk.

Then I upload this image into canva ( http://www.canva.com )where I can basically define it as a YouTube thumbnail which makes it the right size.
I then add any appropriate text and download it to my disk.

I then go to YouTube where I upload the image as a custom thumbnail.

All of this is explained in the video below.

I hope you find it useful.