The dark spots in your example are almost certainly sensor dust, not dust on the lens. Dust on the front element rarely appears as distinct spots because each point on the sensor receives light from across the lens surface.

Best approach:

1. Prevent/fix at the source: clean the sensor carefully, use the camera’s built-in sensor cleaning if available, or have it serviced. A blower may help; if not, use a proper cleaning kit or service center.
2. Use Canon’s Dust Delete Data: many Canon cameras can record dust locations so DPP can automatically reduce those spots.
3. Retouch remaining spots: for visible dust marks, use a healing/clone/spot-removal tool. These are usually easy to fix, especially in even areas like sky.
4. For hot pixels: check whether your camera has a pixel mapping feature in the menu. DPP may handle some hot pixels, but mapping can help prevent persistent ones from showing up.

So: clean or service the sensor, use Dust Delete Data in DPP if your camera supports it, and retouch any leftovers with spot-healing or clone tools.