Ah, So many questions.... Ok, where to start? Are you using an existing
lens? Is it new also? What settings are you using? If shooting handheld are you shooting with a
shutter speed at or above 1/250th second? Do you have a
tripod? if so try that... If not put the rig on a table and take a shot of something, anything, it does not have to be an interesting subject, kitchen cupboards are fine, see if that works? Try Manually focusing the
lens and see if that makes a difference?
Take a shot and post it up with what settings you are using, that will give us a better starting point. The more information you can give us the more we can help. Pretty sure we have all been there at some stage.