It is very simple to add or integrate WordPress blog to your existing website and I will keep it very simple.
You will have two options that you need to decide before you can install or add a wordpress blog to your domain
a) Do you want to add it to your existing website e.g www.yourdomain.com/blog
b) You opt to go and add this as a sub domain to your existing website like blog.yourdomain.com
There are many reasons you should consider and prefer the option (a) over option (b), for example you already have a setup website and you do not want to disturb the current website or you have ads running on your primary domain and if you add a sub-domain as a blog and try to add it Google Adsense you may not be able to take the advantage of your current website history. You can learn more here about Google Adsense for a Subdomain, its advantages disadvantages
Now, Once you have decided to add your new WordPress blog by installing into a sub-folder of your domain here is what you can do
1 – Go to your Hosting cPanel and search for Softaculous Apps Installer and search the wordpress icon
2 – Once you see, click on the icon and it will lead you to the next screen as follows
3 – Click on the install now. The next screen and option is very important and you need to be careful. Once you see the next screen you need to add the folder name where you need to install the WordPress.
Here you can write the directory name, Say you want to make it www.yourdomain.com/blog so write in the blue box and will create a folder. Remember if you leave this option blank the WordPress installation will be done on your root folder and the existing website will be gone. So be careful here.
Follow the installation process and once complete you can log in to your WordPress admin panel and starting posting your blog posts.