I have integrated AdMob in my application. Is it possible to show my own ads using Admob? If not, then what is the best alternative?
Yes! Ad Mob allows you the option of displaying your own ads using the "House Ad Campaigns" option.
That being said, if by "show my own ads using Admob??", you mean display custom ads, then you would probably have to get in advertisers individually and display them using (as @zapl mentioned in the comments) ImageView or something on those lines.
Yes you can. The feature is called House Ads