Onions for Dummies?
 

I've just started to grow onions from seed last year.
I have no idea what I'm doing.
Last year I planted Utah Strain and a green onion (can't remember the name atm).
Last fall, I pulled most out of the ground and most looked like what are called onion sets.
I left some in the garden over the winter and the Utah Strain one has gone to seed.
They look like nice sized bulbs now.
The ones I pulled up last fall are starting to sprout now in the bag I kept them in. (I hadn't had time to replant them this year.)
Can I still plant out these 'onion sets'? Can I use the onions that have gone to seed? I plan on saving seeds, so will the onion still be useable after producing seed?
So many of the websites talk about day length and so many confusing things that I don't know how to make heads or tails of it all!
Can anyone help simplify things for me?
Thanks!
Cathy

I'll try to make things somewhat easier: I should point out I live in Belgium, so my climate and dates could be different from yours;
I sow my onions late february in the greenhouse, plant them outside beginning to mid April, no fresh manure, and my onions ripen off (the stems become brown and dry) end June up to end of July or even later, epending on weather and variety. I let them dry for about a week(outside), and select the finest ,biggest ,healthiest bulbs for seed growing, for each variety 20-25 onions. I put these in seperate boxes and keep them in a relatively cool (no frost!) place, dark and not humid.Next spring I plant out these bulbs after another selection, they start sprouting fromMarch, if they start sprouting I move them to a lighter place. I plant them out from the moment the weater conditions allow some planting, isolate the varieties(they cross easily) and let them grow and flower (normally from half June), the seeds ripen off somewhere in August. I don't use the bulbs for eating anymore, they have lost their taste, become sometimes drier on the inside and there's a lot of cleaning work, so I just remove them.And from then on the cyclerecommences next February,
Frank