How to download an iPhone 4 Theme?

I would really like to get a theme for my iPhone 4, but I ran into some problems. I don't understand what the "jailbreak" thing is or how to do it, then I see that I need to use other things like "Cydia" and apps like "Lockscreen Clock Hide" and "Winterboard." Can anyone baby step me through this? I'm not the greatest with this technology stuff, so thank-you so much in advance for any and all help!

Added note: Is there any way to do this without using any cellular data? My plan does not include unlimited data.

You can't officially get "themes" for iPhone unless you "jailbreak" your phone.

Jailbreak allows you to unlock your phone to third-party tweaks and apps that Apple wouldn't normally allow.

Depending on your system version, you can jailbreak your iPhone 4 via a program called "Evasi0n". This works for iOS versions 6 - 6.1.2

If you are on 6.1.3, you can't jailbreak.

To download themes, jailbreak your phone (if you can), download an app from cydia called "winterboard". Now you can search for themes on cydia and enable them via winterboard

First you're going to need to jailbreak your iPhone. I'm guessing you're iOS 6, but to check go to Settings>General>About and then where it says "Version" That is your iOS. HOWEVER if your iPhone is iOS 6.1.3 or 6.1.4 then it is not jailbreakable. But if you are iOS 6.1.2 or under, then your iPhone is jailbreakable.

If your iPhone is iOS 6.1.2 or under and you are ready to jailbreak, download the jailbreaking software evasi0n from this link: http://evasi0n.com/ (Yes, it's completely safe software)

Once you do that, open the jailbreaking software and then plug in your iPhone. Then press jailbreak. After that follow the on screen instructions evasi0n gives you. (They are simple instructions) This will take about 5-10 minutes to do so.

After that your phone is officially jailbroken. When so, an icon called cydia will show up. Cydia is basically the app store for themes, tweaks(which are when you modify something on your iPhone, like the Lockscreen Hide), apps, etc.

To download a theme the first thing you need to do is download this thing called winterboard. Winterboard is basically the app where you control what theme is on or off or what nod. I would be careful when installing themes because not all themes are very stable(which means can't handle it, so it will crash).So only install the themes with more professional look to it. Usually if a theme when you are adding one has an icon flipping. If it doesn't, most of the time it's not a good theme to download. Also only download the themes that say it's a winterboard theme.

If your phone freezes and has a black screen with a loading icon in the middle, that means it crashed, and it's going into safe mode. Safe mode is when all tweaks, and themes (not apps) are disabled. You can restart your springboard to enable these tweaks again but you should seeing which tweak or theme is not stable enough, and disabling it. Because your phone can get bricked, which means what it says, it will just be frozen and nothing like a brick forever.

There are many cool things about jailbreaking with a few disadvantages. But you need to learn more and more about jailbreaking so you don't mess up your phone. Make sure you know what you're doing. I have been jailbroken with my iPhone 4 for over a year now and I haven't had a single problem because I know what I'm doing. There's youtube videos, articles, alot of stuff you can learn from.