Colours can be a tricky thing so I would suggest that in future when designing a wireframe for your apps you work in grayscale (See step 7 here). This would help you to avoid this problem later on in your workflow as you would have an idea of where to incorporate light and dark values.
In addition, as you mentioned that you are not a designer - instead of using time to make your own colour schemes from scratch, you could try scrolling through colour schemes on sites such as Adobe Kuler. This will give you the opportunity to see how different colours interact with each other or to change the shades on a colour scheme that is close to one you like.
If your interest is sparked though I would suggest resources such as Color for Designers: 95 things you need to know when choosing and using colors for layouts and illustrations by Jim Krause it's a handy book that is broken into concise topics after covering the basics in the first 3 chapters so I tend to use it to thumb through for reference if I'm feeling a little stuck or want something to read :) I've linked his site as he has several other resources (such as Lynda tutorials) that also cover the topic of colour.
Of course this is just one example of multiple resources that are widely available on the topic so I would suggest a little exploring. There is also a great deal of colour theory material for non-designers such as this crash course or books such as The Non-Designers Handbook.
Hope this has been helpful :)