How can I search the contents of the books I added to my Google books? I want to search the contents of the books I added to my Google Books account.

The Google Books web site offers a search my library option. 

But I want to search the contents of the books in my Google Books account from my Android device and from an Android application which is optimized for small screens.
I think your question could be worded better as it seems to ask a couple of questions.

Google books are filed as cryptic alphanumeric IDs, and they seem to be HTML type files it makes it more difficult than with most other book types.


finding books on your device is very easy, use an explorer like File Expert or Astro (both are free, however Astro's search function is better) which contain a search option. You will probably have to use multiple searches depending on how many different types of ebooks you have on your SD card - I know I have epubs, mobi, prcs, pdf, txt and doc files.
If you are looking specifically for just your google books then as long as you have set to store them on the SD card they will be under the following path - Storage Card/Android/Data/com.google.android.apps.books
Searching contents of books within google books - you can't from the library or app itself, unless you are already in the book - in which case press menu and then use search.
However due to the nature of google books you could probably do this much quicker via the website. With other book and file types you could try Astro's search within text - might just pull up what you are looking for as I have had this work on some txt and doc files.