You can have extra withheld from your Full Time job. Depending on what you owed last year and how you are paid (weekly, bi-weekly, monthly) take what you owed and devide it by pays. You can have that amount withheld in addition to what your Full Time withholding by adjusting your W4. Step 4(c). There is also a worksheet for multiple jobs on page 3 of W4.
W4
Top 5 reasons to adjust your W4
Tax withholding calculator