You can customize your own web page to add items to the shopping cart system in PDshop.  There are two ways to accomplish this.  You can use the form "post" method, or you can use an http link.  The required fields to add an item are "itemid", "task", and "qty"

"itemid"
The item id is the unique id number the database assigns when you add a new item to the system.  It is not the same as the item number.  You can locate this id number by hovering over any link to the item.  Example: "somename.com/shop/item.aspx?itemid=5"  In this example, the itemid is 5.

"task"
The task should always be "addnew".

"qty"
The qty, or quantity, must be a number greater than zero.


Example of the Form post method: (insert HTML similar to this into your existing site)
<form method="post" action="showcart.aspx">
<input type="hidden" name="itemid" value="1">
<input type="hidden" name="task" value="addnew">
<input type="hidden" name="qty" value="1">
<input type="submit" value="Add to Cart" name="submit">
</form>

Example of the link method, your link should look something like this:
http://yoursite.com/shop/showcart.aspx?itemid=1&task=addnew&qty=1