what you can see on your image seems to be dust on the image sensor.
To get rid of the dust, you can gently blow it off with a manual blower. It is important, that you do not touch the sensor in any way, because that could damage it.
Usually you can get a little blower at any photo dealer.
The camera has a "Cleaning Mode" in the Set-up menu, register 3. To activate it, the battery needs to be charged sufficiantly.
Take the lens off and enable "Cleaning Mode" in the menu. Then the camera will flip the mirror up, so that you can get to the sensor and you can gently blow the dust off.
Also when changing lenses, have a look at the rear lens element. If you see dust, blow it off or gently brush it off with a soft brush, before attaching the lens.
If you find that the spots do not disappear after trying to blow them off, you should get the sensor cleaned professionally. In general the repair service as well as some photo dealers offer sensor cleaning.