When you have just the journal archive selected to be searched, the actual search criteria will then take into account what you're looking to find. So, if you want to find all messages sent to or from a specific user, use the "To or from" field to specify the SMTP address or addresses of the specific user and run the search. That search will then return only e-mails sent or received by that user. If you have Custodian Manager configured and the user you want is a Custodian, you can specify the Custodian Manager entry for that person to have all SMTP addresses that are defined for him or her used in the search.
So, just specify the user, either by selecting their Custodian Manager entry or by adding their SMTP address or addresses in the 'To or from' field and run the search. You'll likely get 1000's of hits for a open dated search, but that's to be expected of any user who has been sending and receiving e-mails for a long time.
If you only want e-mails to or from that user during a specific date range, just specify the start and end dates for the date range you're interested in, add the Custodian or SMTP address(es), then save the search to start it running.
Note that a date range search can be sped up a bit if you have the Configuration tab's Settings sub-tab, Search section's option "Optimize searches based on oldest and youngest items" enabled as this will allow index volumes that do not have data in the specific search date range to be excluded from being searched. You'll get an Info column entry of "Date range exclusion" for each such index volume.
