If you want to install wordpress on your computer locally. Then you need a software that help you to make you computer, web server.
There is lot of free open source softwares to use your computer as a web server.
But, I recommend one of these, that i used, the name of softawre is xampp. It is totally free and open source.
You can download this from here and https://www.apachefriends.org/index.html and install this on you computer. It takes several minutes.
Here is little about xampp
XAMPP is an open and free source cross-platform internet server solution stack bundle, consisting primarily of the Apache HTTP Server, MySQL database, and interpreters for scripts composed in the PHP and Perl programs languages.
Step to install wordpress :-
1. Install xampp.
2. After the installation you need to start xampp and start apache and mysql module.
3. Download wordpress from wordpress.org and unzip the wordpress folder.
4. Go to the xampp folder where you install this. By default it is installed in c drive always. Find it there and find a folder htdocs inside it and copy entire wordpress files folder here.
5. Type this in your browser http://localhost/phpmyadmin and create database here for you wordpress site.
6. After this go to the wordpress files folder in htdocs and find wp-config.php file in it.
7. Enter db details here, like " db name " the you created in here http://localhost/phpmyadmin for your website and user name, it is " root " always by default here, so type root in user name and leave password field blank. No other modification required here. Save the file.
8. Then type http://localhost/wordpress/wp-admin/install.php this in your browser address bar, if your wordpress folder name is different then write that instead wordpress in address bar, and enter.
9. Wordpress software is running and ask for some details about you site means blog title, user name, password, email. enter all information and hit next. Thats it.
10. Now your wordpress is installed. you type http://localhost/wordpress in browser address bar and you can see, your wordpress site.
For further customization of your wordpress site you need to login in your admin area http://localhost/wordpress/wp-Admin
There is a help video on this topic. How you can install xampp and wordpress on your computer (localhost)
.