By creating such an account you will be able to download ONLY free apps, however you will be able to attach a credit card later should you want to do so.
Tutorial: Step 1
Open iTunes, in the left menu you will find a green icon named iTunes Store and click it. Now you have to choose your country. Click on your country’s flag.
In the upper side you will see a menu with many categories: Music, TV shows, Movies, AppStore, click on the AppStore. After you enter the AppStore, in the left side you will find another menu with apps categories, scroll down until you see a category named Free Apps, and click on a application. Warning! This step is very important, if you don’t select a free app you won’t be able to create the account for free!
Under the name of the app you will find a short description and under it you will see a button containing the price of the app / what you want to download and Buy App/Song/Album. Click it.
You will see a window in which you will be asked to enter your details, and above you will see a button “Create New Account” click on it.
You will see a presentation window, click continue, then accept the terms and conditions. In the next window you have to fill in all boxes. Enter a valid email address because you will have to confirm your account.
If you followed all steps so far then on this page you will see a option named None near the credit card icons, check it and fill in the rest. enter your real home address.
Now you are going to get a confirmation message. Hit done and you will receive a confirmation link in your email address.
After you confirmed your email address you should see a iTunes box asking you to log in!
Congratulations, you now have a free iTunes account without a credit card attached to it that you can use to download free apps!