Withholdings. Please explain it to me like I’m 5. TIA

I live in California. We’re switching payroll companies at work and I need to fill out a new Employee Withholdings Certificate. I haven’t filled out a withholding since I believe the old form. I file my taxes as “Married Filing Separately” due to student loans I accrued before I met my husband who is a much higher income earner. My last withholding seems to be in nearly a sweet spot. I didn’t get much back federally and owed like $75 to the state. I’d like to recreate that on this new form. My husband claims the kids and I make just shy of $70k. Any help would be greatly appreciated?