solder them or get one of those hammer crimpers like copper head showed. soldering is not that hard, its just intimidating till you get the hang of it. i like to strip my insulation on the wires back 1/8" farther than it needs to be, then take my terminal and clamp the tip of it in a vice so that the end that accepts the wire is pointing up. next insert the stripped end of the wire into the terminal and rest the wire over your shoulder or if its too short try to use a piece of wood or a coat hanger bent around the vice to hold the other end of the wire up so it doesnt move around or fall out of the connector when youre adding the solder. once its secured i grab a propane torch ( i have a small butane one that works well on 10-6 ga., but for 4-0 ga ill use the larger bernzomatic torch) and and start applying heat at the base of the connector, slowly working my way to the middle while at the same time pushing the solder into the connector until it flows out of the top. next i slide some shrink tube over the cable and using the distant heat from the torch or a bic, heat the tube till it shrinks.
using this method guarantees 100% connection between your wires and your connector, versus crimping which only captures the outer strands of the wire.