Bee Happy, that's why I don't use horse manure at all, you introduce way too many weed seeds. I stick to cow manure, yes, I have to buy it, but I'm not killing myself pulling weeds all season - well, not as many.
Any new garden area is going to be weedy the first season. Use a long handled cultivator and work through the soil frequently, to bring those weed seeds to the surface and kill the baby weeds. The trick is to stay ahead of them. Pull the seedlings and put them in your compost pile. Then mulch, mulch, mulch, with whatever you have access to. It'll be better next season, provided you don't let those weeds go to seed! I love weeding, but that's part of my gardening disease that few people understand