This tutorial is going to show you how to set the default language and currency in your Magento store step by step.
How To change the default (English) language on the frontend of your site
Step 1: In your Magento admin go to System > Manage Stores
Step 2: Click on Main Website Store under the Store Name (if there are several ones, click any of them)
Step 3: On the next page under Store Information select a different language in the Default Store View drop-down list.
Step 4: Click Save Store.
Step 5: Now every time you are opening the your site, it’s going to be in the language you selected.
Step 6: You can change the default language for the backend by going to System -> Configuration -> General -> Locale options.
How To change the default ($) currency on the your Magento site
Step 1: In admin panel, go to Admin > System > Configuration > Currency Set up.
Step 2: Select currency that you want to be default from your base currency drop down.
Step 3: Select the same currency in the Default Display Currency drop down and from the Allowed Currencies list.
Step 4: Click Save Config.
Step 5: The frontend display currency should be different if you check out your site.
NOTE: Feel free to check the detailed VIDEO TUTORIAL