Summarize this article in one sentence.
It's the app of a circular green icon with three curved black lines on it.  Download Spotify from the App Store {"smallUrl":"https:\/\/www.wikihow.com\/images\/5\/55\/Iphoneappstoreicon.png","bigUrl":"\/images\/thumb\/5\/55\/Iphoneappstoreicon.png\/30px-Iphoneappstoreicon.png","smallWidth":460,"smallHeight":460,"bigWidth":"30","bigHeight":"30","licensing":"<div class=\"mw-parser-output\"><p>I edited this screenshot of an iOS icon.\n<\/p><p>License: <a rel=\"nofollow\" class=\"external text\" href=\"http:\/\/en.wikipedia.org\/wiki\/Fair_use\">Fair Use<\/a><br>\n<\/p><\/div>"} and sign in with the email and password for your Spotify account. You can also sign in with your Facebook account if you've linked your Facebook and Spotify accounts. It's the magnifying glass icon in the bottom-center of the screen. Tap the search bar at the top of the screen and type in the name of the song or artist you want to add to your playlist. To the right of the song you want to add, tap the icon of three horizontal dots to open a pop-up menu from the bottom of the screen. It's the second option on the page, right next to the icon of a music note with a "+" sign on the corner. This opens a list of all your playlists. This adds the song to the end of the playlist you selected, though you can rearrange the order if you want.

Summary:
Open Spotify. Tap . Tap the search bar and search for a song or artist. Tap the ⋯ next to the song you want to add. Tap Add to Playlist. Select the playlist you want to add the song to.