Help adding pictures to webpage

[tomatorhys]

OK as the title says i need help adding images to my html
but i know how to add
img src=""
(part 1)
what i want to do is when i move over a link a corresponding picture is shown eg

game1 (link) = game1.png
game2 (link) = game2.png etc

I know this is going to need a javascript but as my skills in javascript are super limited i dont know how to do this

(part 2)
the secont part of what i want to do is have the picture float on the right side of the screen so when you scroll down the picture floats down to what your looking at (always in view) Some sites have this as a menu or advert but i want to display a picture.

this is yet another javascript.

(part 3)

as i want the picture to change as you move the mouse over a link and i want the picture to be displayed on a floating layer i think i might need another javascript for this.

thanks to all off you that help i am very gratefull
i do have a floating script so you can just post mouseover and how i would go about putting it on the floating layer.

Thanks (sorry long post)