Without knowing the steps you've taken to import data it's a little difficult to identify why it's not there.  The most likely explanation is that the import hasn't been approved. When you've run your import you're given the opportunity to review it. The Summary tab includes three buttons: Approve, Reject and Close. To make the records visible on your database you need to click Approve (presuming you're happy with the way the data has been mapped, otherwise, click Reject and start again).

If this is the cause of the issue, you won't need to run the import again, simply go to the Import Landing Page, open one of your imports and click Approve.

I hope this gets you back on track.