How can you set it up so you can attach a document when inputting lead data

How can you set it up so you can attach a document when inputting lead data

It appears I can attach a document after the lead is created, but not when you are creating the actual lead, I don't see a Upload field option in the customization section. I'm only using free version, is it a Pay feature? If so I'm sold.  Sure I'm missing something, Thanks in advance! 
Dennis