moving between two points over time

I want my character to be able to move between his current position and a set magnitude along the x-axis over a set time, upon pressing the X button. I’ve tried using Vector3.Lerp but no matter how I try it, it doesn’t turn out right. Can someone please tell me how I would go about doing this?

The way I have it now, the character changes position instantly but I want it to be a smooth change.

You can have a look at iTween