I was unable to find a simple explanation of the complete procedure. Decided to attempt this to clear up all the confusion and misunderstanding of the full process.

Need for an upgrade will become evident when the computer seems to take ages to load applications or complete tasks. Or if the existing Hard Drive is almost full. Technology has advanced in recent years with the affordable access to Solid State Drives (SSD) that are replacing old spinning disc Hard Drives.

Step 1: Select New Drive.

Storage Drives are available in several capacities and form factors. Capacities range from about 250GB to 2TB or more.

Form factors can be 3.5", 2.5" mSATA, or M.2 Interface can be either SATA (Serial AT Attachment)or NVMe (Non-Volatile Memory Express) https://www.digitalcitizen.life/m2-vs-nvme-ssd For a table and Sizes See: https://searchstorage.techtarget.com/definition/mSATA-SSD-mSATA-solid-state-drive Selection will depend on mounting available in the Computer. Newer motherboards will have M.2 form factor with NVMe slot. Older boards will have SATA or mSATA. Make sure the Capacity selected is Greater than the Used Space on the HDD to be upgraded. Here I have selected a Crucial 480GB 2.5" SATA SSD. Cost was A$100

Step 2: Install the New Drive.

To minimize disruption to existing setup of Programs and Data on the Computer the preferred option is to Clone the existing drive.

This copies the Operating System (generally Windows) and all installed applications and personal data files and folders to the new drive. To Perform the Clone the new Drive must be connected to the system. Shutdown computer and Disconnect Power. Remove the side panel on the Computer case and look for the SATA headers on the Motherboard or M.2 slot. A SATA drive will need SATA cable and spare Power plug from PSU. Depending on the drive, install in the M.2 slot or in drive bay and connect SATA cable and Power. Once connected Start Computer. Enter Computer Management in the Start Box. In the Control Panel window that opens Select Disk Management. The New Disk should show up in the list of Drives that is created.

Step 3: Cloning Software.

Most Brands will provide access to some form of Software to tranferring data or Cloning an old drive.

Do a Google search with terms like "How to Clone" or "Best Cloning Software" Get familiar how cloning works and the different Software packages. I selected Free Home version of Macrium Reflect. It is available here: https://www.macrium.com/products/home Download and Install the Software and get to know how it operates. When started Macrium Reflect will scan and list all connected drives. If the new drive does not appear, Scan with Disk Management as described in Step2. Then restart Macrium Reflect. It is also possible to re-adjust Partition Size to ensure all the Partitions fit on the New SSD. Select Source disk and Destination Disc and Start Cloning. This will take several hours. Do not switch Off the Computer.

Step 4: Ensure New Drive Works.

To Ensure the New Disk is fully operational, the Old HDD must be Disabled.

There are 2 ways to do this. 1 In BIOS, by setting Boot priority. This can be confusing and Hit or Miss correctly identifying Old and New disk. To Enter BIOS either Del key or F1 needs to be pressed repeatedly when Starting up. 2. I prefer to just open the case and Disconnect the Old HDD by un plugging the SATA data cable and, OR the power cable.

Restart the Computer and Enjoy the New Drive.
Windows automatically Renames the Drive C:>. All application Files and Folders should appear in File Explorer.

Step 5: CleanUp, Dispose or ReUse Old HDD

If the Old HDD was cluttered with a lot of unnecessary files and folders, this is a good opportunity to CleanUP.

Once it is confirmed that the New SSD is Successfull, the old HDD can be reconnected. It will boot with new Drive Letters. After properly identifying and confirming the Old HDD, it can be reformatted and used as a Backup disk. Or it could be setup for Data Storage of Files and Folders. Just go to the relevant Folder in File Explorer. Click on Properties. Use the Location Tab to set the default path to the Old HDD (with new allocated Drive Letter).