Please!

[drHirudo]

Is there a free workbench 3.0 on the Internet

Yes, check out AmigaInABox.

Is there a free program to connect my Amiga to my PC

 Yes, there are many, but you need to specify what cables/connection you have between your Amiga and PC. I can't give you a specific answer here.

[drHirudo]

and I would like to say that I made a Null-Modem Serial Cables

to connect my PC to the Amiga but the problem is that the

Amiga Transfer Program that I got is an EVALUATION VERSION

and does not support the copying of files longer than 1KB !!!

Try TwinExpress or PC2Amiga.
But if your null-modem cable is 7-wire (NOT 3-wire), you can do PPP nullmodem connection to your PC and set FTP server on the PC. Check out Miami Deluxe documentation for more on this and how to do it.