Create Interaction with Drop Down Menus

Hi Guys,

My site is https://paksoftsolution.com/ here you can see some drop down menus

1) Design and Print Media
2) Multimedia
3) Software Dev
4) Web Development

When you click at any one then you can see some drop down list.

Now i want when i click at Design and Print Media > Advertising & Outdoor Media then only specific post appear

“Advertisement & Outdoor Media
We have expertise in all areas of advertisement, Media Planning indoor and outdoor advertisement campaign. From a simple banner design to complex advertisement campaign including Hoardings, Banners, Fliers, Streamers, Billboards, Signboards and Broadcast Media. We can work from your ideas or develop materials of all types focused on invigorating results.PakSoftSolution has its own printing press equipped with latest and most up-to-date Machinery. We have the latest flex printers that gives the highest quality print at an affordable price. So what ever advertisement needs you have, we have the solutions for all your needs under one umbrella.”

Same as when i click at Design and Print Media > Print Media then only specific post appear

“Print Media
One of the most important investments your company can make is developing its image. Business identity is all about visuals and packaging! Strategically and consistently applying a well defined business image across all types of media generates top-of-the-mind recognition in your target audience.

Business Identity Packages
Design and Packaging
Stationary Items
Brochure Printing
Collateral Marketing Material
Product Sell Sheets
Publication Advertising
Product Packaging
Display Graphics
Annual Report Print”

Please Guide me how can i do this.