Although you can use a flash drive to transfer files from one computer to another, if you're transferring a lot of files, try using a USB cable. Unlike a flash drive, there is no limit to the number of files you can transfer from one computer to another with a USB cable. This is because you are linking two computers in real time, not storing files on a device to transfer at a later time.
Turn on both of the computers, log in and wait for the desktop to load.
Install the USB cable software that came with the USB cable on the computer where you will transfer the files.
Insert one end of the USB cable into a USB port on one of the computers. Insert the other end of the USB cable into a USB port on the other computer. It doesn't matter which computer you insert the USB cable into first.
Select the files from one computer that you would like to transfer to the other computer. Some USB cable software allows you to only select one file at a time, while other software allows you to select all of the files you would like to transfer.
Transfer the files by clicking on the "Transfer" option on the USB cable software window. Depending on the software you have, you may also be able to click and drag the files from one computer to another or copy and paste the files. When the transfer is complete, you will see the icons for the transferred files on your new computer's desktop.