Hi, I got my first IPhone 6 for my birthday and unfortunately it fell in water after 6 days. I'm so upset as it was my dream to have one. Please help me and advise what can I do to switch it on. Thanks

Water damage can't be repaired and is also not covered by the one-year-warranty. But you can get a replacement for your phone if you are willing to pay the Out-Of-Warranty-Service fee:

Out-of-warranty repair service
If your repair isn’t covered by Apple’s One Year Limited Warranty, AppleCare+, or AppleCare Protection Plan, your iPhone might be eligible for out-of-warranty service. For example, liquid damage isn’t covered by warranty but might be eligible for out-of-warranty service. Some damage isn’t eligible at all, for example if your device has been broken into multiple pieces. See Apple’s Repair Terms and Conditions for complete details.
Read Apple’s Repair Terms and Conditions

Model	Out-of-warranty service fee	Battery service*
iPhone 6 Plus	$329	$79 *available only if battery fails Apple’s diagnostic test
iPhone 6	$299
iPhone 5s, iPhone 5c, iPhone 5	$269
iPhone 4s	$199
iPhone 4, iPhone 3GS, iPhone 3G, Original iPhone	$149

Plus a $6.95 shipping fee, if required. Fees are in USD and exclude local tax. Pricing is for service through Apple. The final service fee we charge will be determined during testing and may be less than the service fee listed above. Pricing and terms vary for service through an Apple Authorized Service Provider.

copied from Service Answer Center - iPhone

Of course service of any kind from Apple, in-warranty or out-of-warranty, is only valid in the country in which the iPhone was originally purchased.