application/modules/payment_method_walletone/assets/form.tpl
<form id="paidForm" accept-charset="UTF-8" method="post" action="https://wl.walletone.com/checkout/checkout/Index">
{foreach $fields as $name => $value}
<input type="hidden" name="{$name}" value="{$value}"/>
{/foreach}
<div class='btn-cart btn-cart-p'>
<input type='submit' value='{lang('Оплатить','payment_method_2checkout')}'>
</div>
</form>