Soldering is not difficult though it does require a decent soldering iron of 25-35 watts. Try and use non lead based solder as it is less toxic to our enviroment. Warm the wire and feed the solder into the wire.
You can purchase an inexpensive soldering iron for about $10 dollars from your local hardware store.
Soldering is dangerous as the iron gets super hot and it can really leave a burn, so be very careful here.
This project is not intended for young children and should only be pursued by adults interested in growing your own garden leafy greens.