Field value into Code page

You can either query the record from the codepage or pop the data into URL parameters. For example you could do: 

https://yourealm.quickbase.com/db/appdbid?a=dbpage&pageid=your page id&rid=INSERT RECORD ID# here 

and then in your code page you query back to that table and specifically target the RID in the URL param. 

Or you can just shove all the data in the button like: 

https://yourealm.quickbase.com/db/appdbid?a=dbpage&pageid=your page id&field1=info for field 1&field2=info for field 2&field3=info for field 3..... so on and so on

Then you just grab the params and set them as variables to use in your HTML