Iam not able to connect database

[hari78]

i have installed oracle 8i Enterprise Edition on Standalone system with Windows 2000 server OS.

System's cinfiguartion: AMD Athlon 64 x2 with 2.8 Ghz,
1 GB DDR2 RAM,
S-series Motherboard.

I want to install SAP 4.7EE on my PC,so i installed oracle 8i EE prior to SAP.
After complete installtion of oracle 8i,i want to check whether oracle is working or not.So i login to DB using SQL * Plus with userId:System/scott Passwd:manager/tiger and HostString.But iam getting error specifying with error code "TNS Protocol adapter error".
Before installing i have configured TCP/IP attributes using Microsoft Loopback Adapter.

I don't know what to do.
Could anybody help me regarding this issue.

Plz.....plz..

[davey23uk]

did you create a database

[hari78]

no i didn't create the database.Is it mandatory?
I don't know how to create it.
plz explain how to create and login to database

[davey23uk]

well if you didnt create one what are you trying to log into?

use database configuration assistant to create one