How to downgrade iPhone 4S iOS from iOS 7 to 6.1.2 or 6.1.3?

If its require SHSH blobs, please send me the SHSH blobs for iOS 6.1.3. I would be really thankful to you.

Try out this tutorial http://www.redmondpie.com/how-to-downgrade-ios-7-to-ios-6-6.1.3-6.1.2-tutorial/

And check the comments for people offering the SHSH blobs.

You clearly haven't saved your own phone's SHSH blobs, so you are stuck with iOS 7.

You can't import and use them from a different phone.