Hi Roz,
Sorry, I've only just noticed your message.
You can upload multiple photos at a time on the individual race pages (e.g. http://pactrac.co.uk/events/335/) but not from your profile area currently.
However, the multiple uploads only works if you are using certain browsers. This is a limitation of some browsers. In particular Internet Explorer does not support multiple uploads at all (though I believe it may in the version that ships with the new Windows 8).
If you want a recommended browser, Google Chrome (www.google.com/chrome) has been my recommended browser for a couple of years now.
Let me know if that doesn't help.