Mosaic for S1A

Sir, how can I do mosaic for 2 S1A scenes in SNAP

Have you looked at the tutorials mentioned in Sentinel 1 mosaic?

Sir I’m facing these problem while doing the steps which are mentioned in above video.

This problem is happening while doing the calibrate

this is a memory issue. Do you have enough RAM to compute it? Maybe you can create a subset of the area of interest first.