How to rotate video downloaded for correct viewing?

I'm a newbie at videoing on my Canon PowerShot A1300 camera. I videoed the scenes in the portrait screen.

However, upon downloading the video into iPhoto [current version], it downloads it sideways. I selected the downloaded video icon and cose 'ROTATE', but unlike a photo, it did not rotate the screen resulting in one cannot view my video properly. I had made a special trip to a site to do this video with plans to mount it on a website. Unfortunately, unless I can rotate it to be viewed properly, it is of no use to me.

I need assistance on this incident. In other words, by videoing in portrait screen, does this affect the downloading in iPhoto? Or, is there another function I have to engage to have the video download properly for viewing.

If it is a matter of videoing incorrectly, I need to know because I am going to have to make a special trip to the site and redo it.

Many thanks! Appreciate all the assistance I can get to resolve this issue.