iPad can connect to the Internet via both a wireless Wi-Fi network and a cellular data network. When connecting to the Internet via a wireless network, you will not be charged for using the Internet (unless the access point itself charges a connection fee). You will be charged a fee when using a cellular data network, but you can connect to it anywhere you have a cellular signal.
Steps
Method 1 of 2: Connecting to a Wi-Fi network

Step 1. Open the Settings app by clicking on the "Settings" icon on the main iPad screen
If you can't find Settings, then swipe down from the top of the screen and enter Settings in the search box.

Step 2. Tap on Wi-Fi
It's usually at the top of the options list. Make sure the switch is in the On position. It should be green (iOS 7) or blue (iOS 6) when enabled.

Step 3. Connect to the network
To do this, click "Settings", then - Wi-Fi and wait until the list of available networks appears. To connect to a network, just click on its name.
If the network you want to connect to is not listed, make sure you are within range of the network and that it is configured correctly

Step 4. Enter your password
Most networks are password protected, which means you need to enter a password before connecting. If you do not have a password, then ask your network administrator.

Step 5. Check the connection
After entering the password, the iPad will try to connect to the network. If your iPad is able to connect, then you will notice the appearance of the Wi-Fi symbol in the upper left corner of the screen. Open Safari and try loading the site.
Method 2 of 2: Connecting to a Cellular Data Network

Step 1. Make sure your iPad is compatible
Only select iPad models have cellular data connectivity. Your iPad must be able to insert a SIM card.

Step 2. Subscribe to a compatible data plan
Once you've verified that your iPad is data-capable, you'll need to subscribe to an iPad data plan. Not all carriers provide this service, so please visit your local office for available options.

Step 3. Insert the SIM card
You will need to insert the SIM card that you received from the operator to connect to the network. Perhaps the seller will insert the card for you.

Step 4. Open the Settings app
Tap the Settings app on your iPad's home screen. If you can't find the Settings app, then swipe down from the top of the screen and enter Settings in the search box.

Step 5. Tap Cellular Data
This option is usually located at the top of the options list. Make sure the Cellular data switch is set to On. It should be green (iOS 7) or blue (iOS 6) when enabled.

Step 6. Tap "View Account"
On the next screen, tap "Create New Account".

Step 7. Enter your account information
You will need to enter your name, phone number, account login information, and billing information. Your network operator will provide you with your account login information.

Step 8. Read and accept the terms and conditions
After setting up your account, you will be shown the terms and conditions of your plan. Read the agreement and tap I Agree to continue.

Step 9. Confirm the settings
You will be shown an overview of your account settings. Review the settings to make sure you entered everything correctly.
After confirming the settings, you will be notified that your plan is activated. This may take a few moments

Step 10. Decide if you want to enable data roaming
If you go outside the range of your cellular network, you can still receive a data signal. There is usually an additional charge for this, so this feature should only be activated when you are willing to pay the extra money.