If you can't handle the instructions on the W-4 paper form (all 4 pages, not just the front page you turn it), and you can't use the IRS online calculator, you may want to pay a professional for advice.
If your employer won't help you, it's because they don't want to be responsible for your personal finances, and I don't blame them.
For most married couples with no children, you will come fairly close if you each submit a new W-4 with steps 3 and 4 blank, and the box in 2c checked. If your jobs have very different incomes, or if you have large itemized deductions, you will be over-withheld and likely get a refund. If you have other untaxed income (side gig, investments) you will be under-withheld.
