Welcome - it's a bit fiddly adding images but as advised the easiest way is to host somewhere else and link to it.
There a few things which could cause a blurry image:
- missed focus (if manual focus, are you focussing correctly? If using auto make sure you are using the "correct" focus mode - subject to situation)
- moving subject (use a faster shutter speed)
- moving camera (use a tripod/use a faster shutter speed)
- not enough light (results in too slow a shutter speed - up the ISO/open the aperture/use a flash)
- too high an ISO (results in unsharp, mushy photos)
- noise reduction in post processing (also results in unsharp, mushy photos)
- and finally, and almost certaintly not the issue - a crappy lens/camera
The fastest way to knowing which of these it is is to post images with exif data.
Cheers