How to connect LED strips and power supplier

If you need to connect separate LED strips, use plug-in quick connectors. Clip-on connectors are designed to fit over the copper dots at the end of an LED strip. These dots will be denoted by a plus or minus sign. Place the clip so that the correct wire is over each dot. Fit the red wire over the positive (+) dot and the black wire over the negative (-) dot (-).
Remove 1⁄2  in (1.3 cm) of casing from each wire using wire strippers. Measure from the end of the wire you intend to use. The wire should then be clamped between the tool’s jaws. Press down until it pierces the casing. Strip the remaining wires after removing the casing.

Put on safety equipment and ventilate the area. If you breathe in the fumes from soldering, they can be irritating. Put on a dust mask and open nearby doors and windows for protection. Wear safety glasses to protect your eyes from heat, smoke, and splattered metal.
Allow approximately 30 seconds for the soldering iron to heat to 350 °F (177 °C). The soldering iron will be ready to melt copper without scorching it at this temperature. Because the soldering iron is hot, use caution when handling it. Place it in a heat-safe soldering iron holder or simply hold it until it warms up.
Melt the wire ends onto the copper dots on the LED strip. Place the red wire over the positive (+) dot and the black wire over the negative (-) dot. Take them one at a time. Place the soldering iron at a 45-degree angle next to the exposed wire. Then, gently touch it to the wire until it melts and adheres.
Allow the solder to cool for at least 30 seconds. Soldered copper usually cools down quickly. When the timer goes off, bring your hand close to the LED strip. Allow it more time to cool if you notice any heat coming off of it. After that, you can test your LED lights by plugging them in.
Cover the exposed wires with a shrink tube and heat it briefly. To protect the exposed wire and prevent electrical shock, the shrink tube will encase it. Use a gentle heat source, such as a hairdryer on low heat. To avoid burning it, keep it about 6 in (15 cm) away from the tube and move it back and forth. After about 15 to 30 minutes of heating, when the tube is tight against the soldered joints, you can install the LEDs for use in your home.
Connect the solder wires’ opposite ends to other LEDs or connectors. Soldering is frequently used to connect separate LED strips, and you can do so by soldering the wires to the copper dots on the adjacent LED strips. The wires allow power to flow through both LED strips. The wires can also be connected to a power supply or another device via a screw-on quick connector. If you’re using a connector, insert the wires into the openings, then tighten the screw terminals that hold them in place with a screwdriver.