There are a few methods of doing this. The first one is the easiest and the easiest to circumvent. I would make the homepage to be www.google.com and then I would follow these steps to remove the address bar:
1. Open Registry
2. Navigate to HKEY_CURRENT_USER\Software\Policies\Microsoft
3. If you do not find Internet Explorer, create a new key called Internet Explorer and within that create Toolbars and within that Restrictions
4. In Restrictions, createa new DWORD called NoAddressBar
5. Right Click on the NoAddressBar and choose Modify
6. Type 1 in the Value Data (It is preferred that you choose Decimal, although I have checked using HexaDecimal and it works perfectly fine)
7. Close Registry.
Or you can install web filtering software or hardware that will prevent your user from going anywhere else.
Or you can modify your internal DNS to point all websites to Google’s IPs. Remember with any of this situations they will be able to google something but not be able to click through to the site as it will only allow google access.