RE: Is it possible GP use through browser from anywhere ?
Babu Baskaran is correct if connecting via terminal services, you can use a https based VPN firewall solution to connect to terminal services via an in web browser VPN connection.
If you are asking about using the native web client, again it becomes a networking problem, you need to establish a VPN connection to the web server in whatever data centre is hosting it, or your site (use VPN for security and privacy). Obviously you could in theory just expose the web-server to the internet, but relying on the application login for access control alone is a risk I would not even consider!
As usual decisions depends on many factors on which way to tackle it, think about; IT infrastructure, terminal service licencing, IT team experience setting up and running demanding internet applications, number of remote users and how many will be concurrent (for capacity load planning and licencing).
I would recommend you contact a Dynamics Partner experienced in this to get some advice this is a common requirement.