Depending on which licence version of Salesforce CRM you have purchased you may not have the edit option displayed next to the Apex triggers or classes. For those people who are familiar with cloud computing and developing cloud applications, this isn’t too much of a concern (just a pain) when you want to make small changes to code and happy to do so in Production.

My video explains the steps in more detail if you are looking for a basic overview and easy guide on what is needed to get started with Apex and how to edit/create CRM triggers.

It goes without saying (I hope), that if you are new to Apex development you should never deploy Apex code to your production CRM, always sandbox first, do lots of testing then Production.

The basic steps:

1. Download Force.com IDE
2. File->New->Force.com Project
3. Enter your CRM username, password and security token
4. Save

You should then have full access to your Salesforce schema and Apex repository, browse to Src->Triggers and away you go! Once you have finished making changes, simply go to File->Save All. The changes will then be synchronised with your Salesforce CRM instance.

There are loads of guides online concerning Salesforce.com but hopefully this overview will help to fast-track your learning curve.

Does this help? Let me know if more information would be useful.