The best and safest way to eliminate weeds in a vegetable garden is to mulch heavily with newspaper or cardboard or other organic mulch. I personally don't use any herbicides anywhere near where I grow veggies. Commercial growers use them but the home gardener is better to use organic controls.

I also try to stay away from chemical fertilizers, not so much because I fear them as unhealthy but because they are so incomplete. The soil needs lots more than just nitrogen, phosphate, and potassium and that's the basis of many fertilizers. Lots and lots of homemade compost is usually enough to keep most plants growing well. A soil test from a reliable laboratory will tell you if your soil is deficient in any one particular nutrient and how much you need to apply.

To become a Master Gardener, you need to contact your local cooperative extension office and find out if they have the program in your area. If so, you will need to attend a series of classes and then give back a required number of hours volunteering in your community as a Master Gardener. It's lots of work but extremely rewarding. The link below will lead you to your local extension office.

Here is a link that might be useful: Extension offices index