Hey,
I agree with Branta, your duck sounds inexperianced. But experiance comes with practise and she'll soon learn what to do. As laying and nesting make female ducks vunerable, make sure they have plenty of nesting materials and bedding to make laying comfortable and secure.
If you don't want ducklings then you can supply artifical eggs inplace of the ones just laid, or simply take the eggs away. Or, if you want to allow ducklings then you can do this two ways. Either by natural incubation or artifical incubation.
Natural incubation is far easier on your part, and also once the duck gets experiance, she'll be able to do a more accurate job of caring for the eggs and ducklings. But first time mothers do need to be checked regularly.
I actually studied wild ducks for about 6 years before i got some domestic ducks myself, so i had a good idea of duck breeding behaviour before mine started.
Artifical incubation involves more of your time. The temperature and humidity needs to be exact, and monitored/changed at the different stages of incubation.
I hope you have success if you do allow to have ducklings.
I'd suggest that you do as much research as possible into incubation and rearing ducklings, including any and every possible problem that you make be likely to encounter, so that you'll be prepared.
Good luck 
Mel X