XT60 is a very popular battery connector used in RC hobby applications. It is extremely easy to solder, and only requires a few basic tools. Here's how you do it:
1) First, strip about 3mm of insulation from the wire using a sharp knife or wire stripper. Be careful not to damage the inner conductor.
2) Next, tin the wires by heating them with a soldering iron and applying some solder. This will make it easier to attach the wires to the connector later on.
3) Now take the XT60 connector and heat one of the terminals with your soldering iron until it melts the solder that you applied earlier. Quickly place the wire against the molten solder and hold it there until it cools and solidifies. Repeat this process for the other wire and terminal.
4) Finally, inspect your work to make sure that there are no shorts between any of the terminals or wires. If everything looks good, you're done!