[development] Attach a file

I have a custom module with form fields...I want to have file attachment below the form field...My custom module doesn't have any nid.. I tried doing the file attachment without nid...I am getting error... I want the functionlaity that we see when we enable the Upload module and go to create content type like page there we see file attachments... How can I do this for my custom module? Suppose If I create a custom content type and enable the upload module will I get the file attachments option in my custom content type? If so, how can I get this content type into my custom module which has the forms?