My husband doesn't think he can get me pregnant because he has tried having children in the past and it didn't work. ... What can he do to pregnant me?

Get evaluated. You both need an evaluation for infertility. Once the exact problem has been identified, then you can work out how to get pregnant.
Sex. Pregnancy involves proper functioning of both your and your husband's reproductive systems and timing. The best time for you to be pregnant is during ovulation, which you can test with the ovulation kits that are over the counter. If you have sex during the 48 hours around the time your ovulation kit shows positive, you are likely to get pregnant. If no results in a few months, see your doctors.