I'm assuming you have two different computers (an old one and a new one).  Is that right?  Your options for moving files from one computer to another include but are not limited to: 1) copy to a flash drive, 2) copy to a CD or DVD, 3) copy them to an external drive, 4) email them to yourself, 5) upload them to a website such as Dropbox then download them from there, 6) copy them to a Zip drive or some such similar device.  No, you do NOT place your blocks inside the AutoCAD folder or subfolders.  I suggest you create a folder called MyBlocks in the root drive and then when you open AutoCAD go to Options > Files and Folders and in the Support File Search Path use the Add button to add the path to your blocks to the list of paths AutoCAD normally searches for files it requires.  This is a relatively simple thing to do and anyone who has used AutoCAD for more than a year should know how to do.