Q: Where to find battery life percentage? I mean the overall percentage of your charging?

Hi, maryliu12.  

Thank you for visiting Apple Support Communities.  

I need clarification on your question, but it sounds like you are asking how to enable the option to show your battery percentage.  If this is the case, please take a look at the article below.  

Show the battery percentage on your iPhone or iPad

If you are experiencing an issue with the battery on your iPhone, please take a look at the information below.  

Battery or charging issues

• Learn how to charge your iPhone and iPod touch
• Learn how to charge your iPad
• Get help charging your iPhone, iPad, or iPod touch

Issue not solved

If you still have an issue with your device, contact Apple Support.

Get help with hardware features on your iPhone, iPad, and iPod touch

Cheers