Itunes help please.

Hi, I wonder if someone can help me please. I had a desktop with my itunes library on, the music is all on a external hard drive connected to the PC. That PC is now dead. I have a second smaller itunes library on my laptop, with just MP3 format songs which I kept for making discs for my car. When I connect the external HDD to my laptop and open itunes.. it only displays the MP3 format tunes in the original laptop library. How can I get itunes to find the rest of the files (and artwork) from the external HDD.
I should say that I am not brilliant with PC's, so any help will have to be detailed, and step by step please.

Many thanks
Apache100 :questionmark:

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