How to download vidoes to my PC/laptop from a camcorder?

Mmm J

An "analog/digital converter" or "capture card". I use https://smile.amazon.com/Elgato-Video-Capture-Digitise-iPad/dp/B0029U2YSA Blackmagic Design makes a good converter in its "Shuttle" line.

Lord Bacon

You can buy an inexpensive device (that comes with software) that enables you to download the video to your computer and save it in one of the standard formats. Mine was made by KWorld but there are many others. The device has plugs for your camera and a USB for the computer. It might be sold as video capture device or a video transfer device or something like that.

Iridflare

As Mmm J said, you need an A/D converter and, as Lord Bacon said, they can be cheap (£/$25 ish). If you've got a lot of tapes and you want the best quality look for devices that include time base correction (TBC), and expect to pay considerably more!

Jiraiya The Gallant

You should be able to take the SD card out of the camera and insert the SD card into a computer. You can buy a USB card reader for your computer.