I'm assuming you've read Paul's article:
http://www.richsoil.com/hugelkultur/ and it's Premies thread:
https://permies.com/t/17/hugelkultur/Paul-Wheaton-hugelkultur-article-thread
and seen the his video:
There is also this excellent video:
Those form the basis of what to do..... Now....to answer some questions.... As you layer the wood, intermix it with soil and the manure. Cap the wood portion of the mound of with more manure and then soil. A mix of rotten and fresh wood is ok. Cap the whole thing off with the hay for mulch. If it is going to rain just after you build the bed, then mulch it and throw the seed into the mulch and leave it. You can also pull back the mulch and direct plant started plants, trees, shrubs, etc... Don't put the hay under the soil, use it as mulch..... IF it isn't going to rain any time after you want to seed the bed, then throw the seed out onto of the soil, mix it in and wet it down and then mulch it. If you are in a high wind area or if the bed is particularly steep, then it is worth adding the brush over the mulch and pinning it down with nails to hold it in place.
As for what to plant..... at this time of year, in your climate you could easily do potatoes, carrots, beets, any brassicas-esspecially kales--salad greens, etc. But you could also plant it in some cover crops--clover, buckwheat, winter barley, nasturtiums, garden peas, broad beans.... you have lots of options. If it is to be a huge bed with fruit trees, etc....then additionally you could plant apples and cherries later on, or throw some collected seed out into the mound...apples, hazels, damsons, roes, currants.....gooseberries... herbs.... The key is to experiment, observe and have fun! The bed won't thrive this year, but will improve. Good luck!
