I just loaded the 10g client EM on my Windows workstation to connect to our 10g database.
Everything works great except I dont see any place where I can edit records. I have to use SQL Plus to edit records but was hoping to use a GUI like I had with 9i client OEM.
Before we had 10g, I used to have the 9i OEM and it let me edit records in 9i OEM where I could add, delete and update records with a user friendly interface.

Please advise where or how I can edit records in 10g EM or Oracle client?

you can use GUI tools like TOAD or PL/SQL DEVELOPER.

if you want a free tool try SQL DEVELOPER from oracle corporation.

I have instate oracle 9i i want to work in GUI mode Any body can tell me how can I open the GUi mode of sql

or simply RTFM. Instead of the fat clients Oracle 10g uses a thin client web interface with pretty similar functionality to the 9i fat client.

SQL Plus is still available and the preferred way of accessing the database though. Maybe you should learn to use SQL?