i have a DB2 server 8.1 and I want to know (sql query) my actual session ID and the total sessions ID

Is there any way to do that?

Session ID? Do you mean the Application id, like from "LIST APPLICATIONS"?

You can get that from the function application_id() in v8.2:

db2 "values (application_id())"

To get the info for everyone you need to use one of the snapshot table functions.

SELECT * FROM TABLE(SNAPSHOT_APPL('MYDB', -1)) AS SNAPSHOT_APPL