What do I do now that it has bloomed, do I need to dead head it-will it bloom again?

Go ahead and deadhead it, that keeps the plants tidy. You may get some nice rebloom! When I grew it, sometimes it rebloomed, sometimes it didn't.
You could do some research on it to see if it is a reliable re bloomer.
Blooming and then setting seed is a signal that the plant has served its purpose….. it's done what it's supposed to. In annual plants this means the life of the plant is over, and it dies…. Of course with perennials they come back the next year, but with certain perennials if you don't deadhead them they go into a sort of shut down mode…. I always keep all my blooming perennials dead headed. With a very long warm season here I often get rebloom on many of my plants. 😊
Unfortunately this doesn't occur with my iris; they get pretty ratty looking by August.

Yes I am going to dead head it. I just wasn't sure if it was by nature a one and done plant, I just dug it up out of my yard, so it's just a wild plant. I want daisies in my beds but I can't find one at the nursery that I like. Is it just me or do they not even look like daisies any more? double petals, petals that are twisted, yellow instead of white ect. The plants are not attractive at all either. So when I seen this one bloom on the edge of my yard I put it in my bed and saved it from the weed eating! It didn't like being moved of course but it's doing okay and has some new blooms, I will let it go to seed a little and see what happens next year.

I don't like a lot of the newer Daisy cultivars, either. If I were to buy one, I would get that old reliable Shasta Daisy Alaska, I think it is.
Ox eye daisies grow wild here too,msome folks consider them invasive. 😁 There are great swaths of them around overpasses on our freeways. Just gorgeous ! I'm pretty sure they set a lot of seed; plus the clumps get larger every year. Why not just let the last flowers of the season go to seed? That's what I do with my common purple echinaceas; I usually have lots of seedlings the next spring.