Some great links from Backyard Gardener.* As to your question about starting now or having to wait:* You can start this year, but add at least 4" of compost to the planting beds and mix it in.* You can start your own compost piles to use next year, but you can purchase it in bulk or by the bag now.* Here's a compost calculator.
You can also use the lasagna compost method over the winter for next year.
For purchasing seeds and plant material you can search here and check references.* You can also look for local mailorder by state.
Be sure to read through other posts here as there are other good links too.* Oh, and welcome to the wonderful world of gardening!
When weeding, the best way to make sure you are removing a weed and not a valuable plant is to pull on it. If it comes out of the ground easily, it is a valuable plant.