Note: These screenshots were taken in the Instagram application on iOS.
Step 1: Tap the magnifying glass at the bottom of the screen.
Step 2: Tap the search bar at the top of the screen.
Step 3: Enter the keyword you want to search for.
Step 4: In the search results that appear, tap the keyword you want.
This will bring up a feed of content related to the keyword you selected, and you can tap even more keywords at the top of the screen to see related content.