Android - Read an XML file with HTTP GET

I need to explore for my project use of web services on Android. I know that there is no official library for XML - RPC web service.

But there is for REST XML and i need to test it.

I would like to read XML on my web page (Where i have to pass username and Password) from Android with HTTP GET.

OR

Suppose, i follow This link, then where do i pass username and password?

Can anybody help me on this.