It would be helpful to know the camera model number.
I am going to guess you have a DSLR camera.

If so,

You likely have dust on the mirror or dust on the MOS sensor.
Your camera instructions should have directions for cleaning those parts.
Follow those instructions.

If you have a point and shoot type camera you likely have dust on the front of the lens (glass).
Examine and clean with a soft dry cotton lint free cloth.
You can breathe on the lens to add some moisture to help with the cleaning.
Gently clean the lens, don't scrub it.