Is there a page like this one for linkpoint
No...at least not yet anyway. Originally, we didn't really have a need to create a whole reference page for setting up the Authorize.Net interface, because there were no settings on the Authorize.Net side that had to be configured to interface with uShop (unline the LinkPoint interface that requires you to name specific variables). You just simply filled in the Authorize.Net payment option setting on the uShop Control Panel... and that did it.
Recently, however, Authorize.Net has required that you specify the Referring URL of your uShop CGI script... so that it can verify that only your uShop CGI script is trying to POST orders to your account... but I think that is still the only required "setup" you have to do now on the Authorize.Net side. We'll still see about creating a referrence page with some screenshots.
In the meantime, are you having any specific problems with the interface? We should be able to assist.
On the url page it has 6 boxes. Which ones do I check?
The control panel has these two fields
I understand the Merchant ID.
What do I put in the Customer ID?
The customer ID can be any identifier you want. It is typically used to help you distinguish which orders were received online.... and which orders were received via phone and entered manually (by you) on the Authorize.Net virtual terminal.
The default value for the Customer ID is "Online Customer"... so that later when you view transactions via your Authorize.Net virtual terminal... you can easily identify which customers were from online.
In your Authorize.Net account settings, the following two fields should be checked in the "Manage URLs" area:
1) Valid Browser Referrer URL
2) Valid ADC or Receipt Link URL
Also, make sure the "URL" is the exact URL of your uShop CGI script.