I need to reimburse an employee for expenses that they paid for with their own cash... it says to issue a check for reimbursement and journalize this cash purchase of merchandise... when issuing a check on the check stub who do I write the check to and what is it for and when journalizing it what ledger do I write it in

You write it out to the employee, note for expenses and what they covered (have you got his receipts to validate the expenses?). It goes in the general ledger.

You would:
Dr. Whatever they bought for the company.
Cr. Cash... write the cheque to the employee, for reimbursement purposes as the note on the memo portion of the cheque.