Oracle Database Express Edition (XE)

I'm a Newbe in Oracle .. sorry..
So how to build the connectionstring. Its so pretty easy in MS Access what I did the last 15 years. I cannot find out. I never have given this database a name during installation. When connecting to the database: whats the databasename itself. ?? Which path has to be set in the connection String
My Oracle 10g is installed on c:\oraclexe\... Whats the database file. In Access easy : its the .mdb file and here. ???

Do I have to do some specific actions when I have finished the 10g setup, before I can access with ADO ?
There is an example in it where user is 'hr' password = 'hr' so please tell me how to access this with a normal conectionstring in ADO technique.
Thx in before