SharePoint: Enabling Anonymous Access on a Site Collection

First, you need to configure the web application for anonymous access:

1. go to Central Administration
2. go to Application Management
3. click on Authentication Providers
4. choose the Web Application the site collection lives into
5. click on the zone for the specified provider
6. check Enable Anonymous Access and Save

Then, you need to enable anonymous access in the specific site collection:

1. Go to Site Actions Site Settings Modify All Site Settings
2. Click on Advanced Permissions
3. Click on Settings Anonymous Access
4. choose desired anonymous access, then OK