How Orthorectify a GRDH image

How can i orthorectify a GRDH radar image?
How many differents ways can i do it?
Only range doppler tarrain correction?

SNAP supports Range Doppler Terrain Correction and SAR Simulation Terrain Correction.
Please have a look at my post on the differences between both: SAR Simulation Terrain Correction

Very useful info.
Thanks a lot.

Study the tutorials please.