Server Error When Click To Order

[clriding]

Hi,

So I am not a developer or designer. I have very limited understanding of codes etc... please can someone help me and reply with a laymen's response  I don't understand the errors that show up when put site in debug mode... I've tried and it's like looking at goddlygoop....when I add a product to the basket and proceed to checkout, after I've put my address in and click 'continue' - it throws up a 500 server error page.....

http://essentialforyou.co.uk/gb/order

I've looked at this file ObjectModel.php and still not sure what I'm supposed to do or input? None of the below makes sense. Can someone direct me please?

Regards, Claire

WITH DEBUG MODE:

[PrestaShopException]

Property Address->id_country is empty.
at line 1003 in file classes/ObjectModel.php

998. } 999. 1000. $message = $this->validateField($field, $this->$field); 1001. if ($message !== true) { 1002. if ($die) { 1003. throw new PrestaShopException($message); 1004. } 1005. 1006. return $error_return ? $message : false; 1007. } 1008. }

ObjectModelCore->validateFields - [line 292 - classes/ObjectModel.php]

ObjectModelCore->getFields - [line 559 - classes/ObjectModel.php]

ObjectModelCore->add - [line 187 - classes/Address.php] - [2 Arguments]

AddressCore->add - [line 516 - classes/ObjectModel.php] - [2 Arguments]

ObjectModelCore->save - [line 74 - classes/form/CustomerAddressPersister.php]

CustomerAddressPersisterCore->save - [line 159 - classes/form/CustomerAddressForm.php] - [2 Arguments]

CustomerAddressFormCore->submit - [line 90 - classes/checkout/CheckoutAddressesStep.php]

CheckoutAddressesStepCore->handleRequest - [line 59 - classes/checkout/CheckoutProcess.php] - [1 Arguments]

CheckoutProcessCore->handleRequest - [line 264 - controllers/front/OrderController.php] - [1 Arguments]

OrderControllerCore->initContent - [line 292 - classes/controller/Controller.php]

ControllerCore->run - [line 515 - classes/Dispatcher.php]

DispatcherCore->dispatch - [line 28 - index.php]