Android Touch

What i would like is a GuiTexture on the screen which is an image of an arrow. I would like it so when the user touches that arrow it will move a sphere or other object to the right or left. If you hold it i would like it to continue moving so it would have somewhat something to do with the update.

How would i go about doing that what method would it be its as simple as:

 If Guitexture is touched
 Move the sphere in the right direction
 end if

im not quite sure what code i would use though