I'm assuming you mean your laptop 2.5" HDD has about reached it's capacity. What kind of laptop do you have, and what is the name, model #, size of the new HDD you purchased?
Most times, the drive manufacturer has a cloning app that can copy over the old drive data to the new drive, which you can download from their website, or it can already be on an accompaning CD. With the app, you can clone the data over a couple different ways:
Remove the HDD. Attach both the old HDD and new HDD to a desktop computer, and booting to the CD/DVD drive, clone over the old HDD data to the new one. Then replace the new HDD in the laptop and reboot.
Remove the old HDD and replace it with the new HDD in the computer. Attach the old HDD using a SATA connection or USB connection with adapter to the computer. Boot up to the CD/DVD drive (using the cloning app) and clone the old HDD to the new HDD. Then remove the old HDD connection and reboot the computer normally with the new HDD as the 1st boot drive.