I need advice about my website which is hosted in Google Apps (free plan).

Currently I use a domain name called "A" and have already added another domain name called "A+" as a secondary domain in my Google Apps account. I set my email accounts with this "A" and "A+" domain name.

How do I set the domain name "A" so when my web visitor accesses it, it will automatically forward to the "A+" website? Will my emails still work properly without any problem?