How to change my ringtone on iPhone 5 to a song I want?

I don't like the ones that are on it and i want to change my ringtone but idk how

1) Go to the App Store
2) Download the App Ringtones
3) Make sure the song you're wanting to use is in your iTunes and synced to your iPhone
4) Open the app Ringtones
5) Select the option use from iPod Library
6) Select the start and stop points of the song by dragging the selection bars along the course of the song
7) Trim it where necessary (by dragging each end where you want the song to be started and stopped) Can only be less than 30 seconds
8) Click on the save button (looks like a floppy disk
9) Plug your iPhone into iTunes
10) Go to file
11) Create new folder
12) Label it ringtones (it'll automatically rename it Tones)
13) Go to your iPhone under Devices
14) Click on Apps
15) Scroll down to file sharing
16) Click on ringtones
17) Click on the ringtone you just made
18) Click on Save To (I'd recommend your desktop)
19) Drag that file that's on your desktop into the Tones folder
20) Open the tones folder and drag that song onto your iPhone that's in the devices tab
21) Sync your iPhone

Assigning your Ringtone:
1) Go to Settings
2) Go to Sounds
3) Click on the one that says Ringtone
4) Select the one that you want