New campaign doesn't show up
There are many things that could be the issue. If you are running display, then it would be hard to stumble upon your ad.
If you are running a search campaign, are you trying to search for a keyword in your account to see if the ad shows? It won't receive an impression every time it's searched.
So instead, the first place to start is using the "ad preview and diagnosis" in the "Tools" menu at the top.
Make sure the settings on the left would be included in your campaign settings. For instance, if you are targeting the United States in your campaign, choose the United States (or at least some place in the US). Same thing with language and device. Once you search in that tool a message will be at the top telling you either your ad is showing, or it's not and why it isn't.
Best of luck.