Thanks for the reply. The tracks are in .aiff format and are on an external hard drive as there were rather a lot in total. I shall try importing a selection into Music on my wife's MacBook Air and then make them into a playlist. Am I right in assuming that this will allow the tracks to play one after each other? Hopefully that will be straightforward - but watch this space for yells of dismay!
Yes, creating a playlist will allow the tracks (and only these tracks) to play one after the other.
If you are using the Macbook air as the playing device, then you are doing the right thing.
If however you intend to load them onto a memory stick to play them on some other device then..
What is the other device?
If it can play .aiff files, then you could just use finder to drag them from the external HD to the memory stick, without the need to go via the music app.
Overall, I would suggest using the Macbook air as the player will work for sure. Any other approach may be troublesome, due to Apple's insistence in using non open standards such as .aiff
I must protest Richard's description of AIFF as non-open standard: you can find the standard referenced on the Wikipedia page for AIFF.
Apple does many bad things but closed audio-file formats are not one of them. It uses AIFF (based on an Electronic Arts format), AAC (part of the MPEG standard) and Apple Lossless (ALAC, usually in an mp4 container file).
AIFF just contains PCM data (the same stuff as on a CD so it can contain a "perfect" copy of a CD). That leads to large file sizes. If you have golden ears and can hear the difference between 256kb/s AAC and CD quality then I would advise transcoding to Apple Lossless. This gives smaller file sizes with no data loss (the data is rearranged but none is discarded, unlike MP3 or AAC).
ALAC is a proprietary Apple format but an open library allows pretty much any music player to read/play it (eg MS Windows) or the Music app can transcode it to AIFF or AAC should you need it.
Ok, I got the open standards bit wrong. However, I think the rest of what I said is correct. Also, just because a standard is open and therefore allows any music player to read/play it does not mean that a particular music player actually supports it.