Log into the reporting services as administrator, you should have all the options available to you. Once logged in add the appropriate user by performing the following steps:
1.Open the Report Manager with administrator privelege.
2.In the Home page, click "Properties" tab.
3.Click "Security" tab.
4.Click "New Role Assignment".
5.Type the certain users(or the group of these users) in the "Group or user name textbox".Do this even if the target user is already in the administrators group
6.Check the "Browser" role or any/all roles that are appropriate
7.Click OK to apply.
Log in again and you should be all set