This wikiHow teaches you how to view your iPhone's storage usage and downloaded music and apps on your iPhone.
Steps
Part 1 of 3: Viewing storage usage

Step 1. Open your iPhone's settings
It's the gray gear icon on the home screen.

Step #2. Tap on General
It's at the top of the Settings page.

Step #3. Tap on Storage & iCloud Usage
You will find this option at the bottom of your screen if you General opens.

Step #4. Tap on Storage Manager under 'Storage'
This is the first Storage Managementoption on the page.
The lower part of the information pertains to iCloud. Downloads from iCloud are not saved directly to your iPhone

Step 5. Browse your saved information
Here you will see a list of all the apps currently on your phone. On the right side of each app, you'll see the amount of space it's taking up (e.g. 1GB or 500MB).
Since there is no "Downloads" folder for an iPhone, all downloads (e.g. documents) are calculated in the size of their corresponding app (e.g. attachments in Messages add to the space that Messages takes up)
Part 2 of 3: Viewing downloaded music

Step 1. Open your iPhone's music
It is the multicolored musical note icon on a white background.

Step #2. Tap on Downloaded Music
It's above the "Recently added" heading on the library page.
- You may need to tap in the lower-left corner of the screen first Library to tap.

Step #3. Tap on a music option
These include the following:
- Playlists
- Artists
- Albums
- numbers

Step 4. Scroll down to browse the music you downloaded
Any music currently on your iPhone's hard drive will be listed here.
Part 3 of 3: Viewing downloaded apps

Step 1. Open your iPhone's App Store
It's the white 'A' on a light blue background.

Step #2. Tap on Updates
This option is located in the lower right corner of the screen.

Step #3. Tap on Purchased
This is at the top of the screen.

Step #4. Tap on My Purchases

Step 5. View your downloaded apps
Any app with OPEN to its right is currently on your phone, while apps with a cloud and a downward pointing arrow next to them are previously downloaded apps that you no longer have on your phone.
- You can also click Not on this phone Tap at the top of this page to view apps that aren't on your phone that you've previously purchased (or downloaded).