Select ui slider to change float value?

Hello i have a slider in my scene and i want it to change a float value from 1 to 3. But i dont know how to do this. If you can tell me how please do so, and use pictures! Thanks.

here is my code if needed:

var Crosshair1 : GameObject;
var Crosshair2 : GameObject;
var Crosshair3 : GameObject;

var SliderValue : float;

function Update ()
{
        //crosshairs
	if(SliderValue == 1)
	{
		Crosshair1.SetActive(true);
		Crosshair2.SetActive(false);
		Crosshair3.SetActive(false);
	}
	
	if(SliderValue == 2)
	{
		Crosshair1.SetActive(false);
		Crosshair2.SetActive(true);
		Crosshair3.SetActive(false);
	}
	
	if(SliderValue == 3)
	{
		Crosshair1.SetActive(false);
		Crosshair2.SetActive(true);
		Crosshair3.SetActive(false);
	}
}

//crosshairs
function ChangeToCrosshair1 ()
{
	SliderValue = 1;
}

function ChangeToCrosshair2 ()
{
	SliderValue = 2;
}

function ChangeToCrosshair3 ()
{
	SliderValue = 3;
}

1: Go to GameObject > UI > Slider.
2: Set your upper and lower bounds as shown below.
slider settings

3: Then you can access the sliders current value in your script with something like this:

var sliderObject : slider = GameObject.Find("name of your slider").GetComponent(Slider);
SliderValue = sliderObject.value;

Now, your SliderValue variable should always be the same as the slider in the scene.

Possible helpful video: https://unity3d.com/learn/tutorials/modules/beginner/ui/ui-slider