Duplicates through conditional formatting

I have two columns of data. What I want to be able to do is look up the value in A1 and see if it appears anywhere in column B. I then need to color A1 red if it does appear in column B.

I am a bit of an excel novice and did try to search but could not find anything specific to comparing 2 lists.

Any help would be appreciated.

Thanks
Jonathan

Thanks for the link VBA Noob.

Now working.

Jonathan