Right on, Ingrid!
Recommended resolution for internet photos (etc) is 72 dots per inch. This keeps the filesize down and, consequently, the send time is reduced.
This is also a handy thing to remember if your recipient is using an e-mail account with a limited capacity (e.g. Hotmail) - you won't take up so much of their allocated space.
I did do an NVQ course on Info Tech, but it was 5 years ago and done on a PC - and I haven't had hands on a PC since. This is a Mac, and I've had to learn everything the hard way (University of Trialanderror). Never worry about being less knowledgeable - we were all like that when we started! You'll get these things as you go along - and you'll find people all over who can give you a bit of help (like on this chummy board!).

Snorri
Twilight Zone autodidactic
:D hee hee, look it up! :D