Many variations on the MacKenzie tartan exist. Two of the most popular versions are shown here.
This tartan is also known as the Regimental Tartan of the Seaforth Highlanders.
Dress MacKenzie Tartan
The dress tartan is worn for more formal occassions.
There is more information on tartans here.
Kilts are often worn at formal Scottish occasions, and look very smart when worn correctly. There are various myths and opinions on kilts, and it is recommended that you so some research so that you are comfortable wearing it — and comfortable answering any questions!
There is a website full of advice about kilts at http://www.your-kilt.com.