The form for web payment standard with Sandbox of Paypal.

Paypal

<form action="https://www.sandbox.paypal.com/cgi-bin/webscr" method="post" accept-charset="utf-8">
	<input type="hidden" name="business" value="Mail address of Seller" />
	<input type="hidden" name="item_name" value="Item Name" />
	<input type="hidden" name="amount" value="Item Amount" />
	<input type="hidden" name="quantity" value="1" />
	<input type="hidden" name="currency_code" value="JPY" />
	<input type="hidden" name="lc" value="jp_JP" />
	<input type="hidden" name="charset" value="UTF-8" />
	<input type="hidden" name="cancel" value="http://example.com/cancel.html" />
	<input type="hidden" name="return" value="http://example.com/success.html" />
	<input type="hidden" name="notify_url" value="http://example.com/ipn_paypal.html" />
	<input type="hidden" name="cmd" value="_xclick" />
	<input type="submit" name="submit" value="Send" />
</form>