Oracle Database Discussions

Ze story so far - newbie to all this but first had problem with

CREATE SMALLFILE TABLESPACE "MAC" DATAFILE

tried recovery and restore then got the following error when I tried to startup:

ORA-01589: must use RESETLOGS or NORESETLOGS option for database open

dropped tablespace and was going to recreate it but couldn't get it to startup:

then tried to alter database open resetlogs;

ERROR at line 1:
ORA-01152: file 7 was not restored from a sufficiently old backup
ORA-01110: data file 7:
'/export/home/training/product/10.2.0/oradata/training/users02.dbf'

DOING MY HEAD IN, going around in circles for hours, I know it is something basic and stupid:

tried full restore, incomplete recovery from SCN, tried taking taplespace offline, this is just a practise DB....

ANY IDEAS,

THANKS