Giving your customers the ability to add multiple items to their cart at one time is very simple. Instead of putting each item in their own form tag (i.e. <FORM > </FORM>) All you need to do is put all the items within a single form tag.
Here is an example:
<FORM METHOD="POST" ACTION="http://www.myshopcart.com/cart/shop.cgi">
<!--FIRST PRODUCT-->
How may products?
<INPUT TYPE="hidden" NAME="merchant" VALUE="Merchant_Name">
<INPUT TYPE="text" NAME="item-Product_ID|Price|Produce_Name|Weight"
size="3">
<P>
<!--SECOND PRODUCT-->
How may products?
<INPUT TYPE="hidden" NAME="merchant" VALUE="Merchant_Name">
<INPUT TYPE="text" NAME="item-Product_ID|Price|Produce_Name|Weight"
size="3">
<P>
<!--THIRD PRODUCT-->
How may products?
<INPUT TYPE="hidden" NAME="merchant" VALUE="Merchant_Name">
<SELECT NAME="item-Product_ID|Price|Produce_Name|Weight"
<OPTION VALUE="0">0</OPTION>
<OPTION VALUE="1">1</OPTION>
<OPTION VALUE="2">2</OPTION>
<OPTION VALUE="3">3</OPTION>
<OPTION VALUE="4">4</OPTION>
<OPTION VALUE="5">5</OPTION>
<OPTION VALUE="6">6</OPTION>
<OPTION VALUE="7">7</OPTION>
<OPTION VALUE="8">8</OPTION>
<OPTION VALUE="9">9</OPTION>
<OPTION VALUE="10">10</OPTION>
</SELECT>
<P>
<!--FOURTH PRODUCT-->
How may products?
<INPUT TYPE="hidden" NAME="merchant" VALUE="Merchant_Name">
<INPUT TYPE="CheckBox" NAME="item-Product_ID|Price|Produce_Name|Weight"
Value="1">
<P>
<INPUT TYPE="submit" NAME="add" VALUE="Add to Cart">
</FORM>
This is what the code above would look like: