If you want to move your old WordPress website youroldsite.com to the new domain yournewsite.com, then you must have a web hosting account and you should familiar with your web hosting control panel.
There are some steps which you should keep in mind while moving your WordPress website to a new domain
1. Create a backup of your whole Website
The first and most important point is that you have to create a backup of your whole WordPress website. There are many plugins and solutions out there that allows you to create a backup of websites. You can use BackWPup, VaultPress, BackupBuddy or WordPress backup to Dropbox.
2. Moving your old WordPress site to new domain
In second step you first need to install and active Duplicator plugin have to start migration process. After installation click on the Duplicator menu, and simply click on the create button to create a new package.
3. Setting up Permanent 301 Redirects
The third step of setting up a permanent 301 redirect is very important for both user experience and SEO. This allows you to redirect users and search engines to your new site. You need to connect to your old site using FTP. Go to wp-includes or wp-admin folder and paste the following code in .htaccess file at the very top:
#Options +FollowSymLinks
RewriteEngine on
RewriteRule ^(.*)$ https://www.yournewsite.COM/$1 [R=301,L]
4. Notifying Google About the Change
In fourth step, Log in to your Google Webmaster Tools account and write your change of address. Go to left menu under configuration -> Change of Address. Yes, you have to verify your new site, so go ahead and do it.
5. Notify your Users
In the end, you have to make a public announcement about the migration of your website. For announcement you simply have to write a blog post on your new website. This can be helpful for your users in a lot of ways.