Point in time database restore
For a point in time recovery, you need the series of transaction log backup files that are usually generated by regular, scheduled transation log backups in addition to the full database backup that you possess. Transaction log backups are often denoted by .bak or by .trn extensions. If you do not have those transaction log backup files, you can't do what you want. Roughly speaking, you would restore to a point in time by:
1. Restoring the full backup file using the NORECOVERY option.
2. Restore all of the relevant transaction log backups using the STOPAT option. 
3. Lastly, bring the database out of recovery.