working on html dom table rows

[christine clarin]

hello, i have been working on html doms using javascript. everything is well, until i encounter this: i have a table where in i need to change a row's background color everytime i specify a row number (this row number would identify which row should change background color). i get to do this but i have these problems:

it only happens for rows which i haven't set my background color yet (i have already formatted my html using css wherein each row is alternately colored in gray) [see picture]. Why is that? what should i do to remedy this?

when a different row number is chosen after another, the background color previously set for the previous row remains, what i want is for the new background color to completely transfer to new row specified and the previous row be returned to the original color it was in. how do i do this? thanks.

I really hope you get to help me on this one because I'm really stumped! thanks!

[christine clarin]

i forgot to include the picture, here it is: