You can buy seedlings from the nursery, but they are quite expensive. You don’t want to be put off if things don’t work out in your first year. Thinking about the waste of money doesn’t help you stay enthusiastic. A good way to start of growing your own food from seed is to buy one of these off e-bay. 
It’s a reptile warming mat. You can see them here Free shipping too! They are under $10 (NZ) and absolutely perfect. A propagation kit or seed-raising mat can be up to $200, but this is just as good. Set it up somewhere with good light, and then grab a couple of take-away containers with lids. Turn them upside down, and get a couple of paper towels.
Write on the paper towel what seeds you are planting, and then line the lid of the container with the towels. (This example is of three different tomato seeds). Wet the paper towels, sprinkle a few seeds onto them, and pop the base on, which is now the lid. Place on the mat, and leave to sprout! Check them every day. They should remain moist, but may need a top up. If they do, tip water under a corner of the towel so as not to disturb the seedlings. Just enough to moisten the paper towels.
When the seedlings have sprouted, they need to be transferred into good seed-raising mix with tweezers, and left somewhere warm to grow. I’ll show you how to do this next time.