"How do I type accents in French?" This is a commonly asked question and I've put together some links to pages which should help.
The page I use most and which certainly works on my computer is:
I've printed out the list of codes and keep it above my computer. I use them so much that I use several without needing to look up the code.
The most common accents I use and have learnt are:
If you are using a laptop the following stie might be of more help: