In the left pane three items are highlighted first one is ‘Installed Plugins’ which is displaying all installed plugins in your website, second one is ‘Add New’; screen allows you to add new plugins and last one is ‘Editor’; Editor is using the Plugins Editor Screen, where you can modify the source code of all your plugins.
There is two defaults plugins is visible first one is ‘Akismet’ and ‘Hello Dolly’. These plugins are included with the WordPress core distribution. Let’s see the brief description on it.
‘Akismet’: It checks your comments against the Akismet web service to see if they look like spam or not. You can review the spam it catches under "Manage" and it automatically deletes old spam after 15 days.
Hello Dolly: This is not just a plugins, it symbolizes the hope and enthusiasm of an entire generation summed up in two words sung most famously by Louis Armstrong. Hello, Dolly. This is, by the way, the world's first official WordPress Plugins. When enabled you will randomly see a lyric from "Hello, Dolly" in the upper right of your Administration Panels on every page but the Plugins panel.
If you want to create your own plugins then WordPress provides to you, three options;
1. Writing a Plugins
2. Plugins API
3. Plugins Resources
Here you can select many more option to add new plugins in your website such as:
1. Search Plugins: The ‘Search’ screen has options to search the WordPress.org Plugins Directory for a particular Term, Author, or Tag. You can also search the directory by selecting popular tags.
2. Upload: Through the upload option, you can upload your own plugins into the website and also install it.
3. Editor: You can use the editor to make changes to any of your plugins’ individual PHP files. Be aware that if you make changes, plugins updates will overwrite your customizations.
Choose a plugin to edit from the menu in the upper right and click the Select button. Click once on any file name to load it in the editor, and make your changes. Don’t forget to save your changes (Update File) when you’re finished.