I have SQL Server 2008 with BIDS, I have installed sql server myself and i am administrator of machine. Now I am able to make reports using BIDS, I am also able to login(windows authentication) to report server using SSMS, but when i try to access report manager URL it asks me for Username/passowrd. I am not sure what to give there as till now from SSMS i could manage with windows authentication for database engine.
SSRS always uses Windows authentication so your user name and password that you're seeing is your Windows login. There is no separate account just for Report Manager. If you're seeing a prompt, you might have UAC enabled and it's prompting you because of that. Or your browser is not enabled for Windows integrated security. You can add the Report Manager URL to trusted sites or Intranet sites if you're using IE.