This is what the "basic" code looks like...

this is your Code..
<url><MARQUEE banner><I can scroll across and IM window...



Adding Backgrounds to the scrolling text...

Code...
the bgcolor= tag is what allows you the change the background colour, simply enter the colour code for the required colour
<url><marquee bgcolor="#80FF00"><I can scroll across an IM window...and add a background colour

here is the code with the bgcolor tag in place AND also the font color= tag to change the colour of the text, the colour code "FFFFFF" is for white text, the <b> tag makes the text bold
<url><marquee bgcolor="#800080"><font color="FFFFFF"><b><purple background with BOLD white text...



Direction and Behaviour of the scroll...
Direction...

Code...
if you leave the code as is it will use the default which is from the left..
<url> <marquee banner><I default to the left...

if you wish to stand out from the "norm" and scroll from the right instead then use the tag direction="right"
<url> <marquee direction="right"><but can go to the right...

Behaviour...

Code...
the default will scroll..
<url> <marquee banner><my default is scrolling....

but by using the tag behaviour="alternate" it will appear that the text is bouncing from side to side...
<url><marquee behavior="alternate"><but i can also bounce