Put command syntax is

• put expression preposition destination
  

e.g.:

• put 256 into card field 3
  

A field can be a container, as in this example, or it can be an object, even an object that has a script. If so, then you can reference it (assuming it is field 1) in a put command simply as:

• put field 1 into destination
  

I just tried this in a dummy stack and it works, but I had to specify the destination, as in:

• put field 1 into card field 3
   
  or
   
  put field 1 into background field 3
  

Hope this helps.