First make sure the adjuster tabs come up on your new cable
In this picture one is wrong (black) and one is right(white). On the new cable they can get a little sticky so you may need to wiggle it a little to get it to come up. When mine were like this it wouldn't go very well into first; it would only engage first when coming from second.
Then grab a buddy and adjust the cable. Keep adjusting the cables and having your buddy try the gears until it is right. You can try the neutral method, (have your buddy hold it in neutral and you adjust the cables 'til the shift towers are vertical), or you can use the fourth gear method. Link is here