create a media pools and assigned ,format the tape and assigned them to the media pool , by defult the tape will have a retention of 6 day this mean it will be overwirten after 6 days is this way your daily backup will be overwriten after 6 days you can also modify the retention period to whatever you like.
if you you Rotantional schedule then you can enable GFS and it will take care of Monthly,Weekly ,daily retentions period.