How to fix screen resolution ( has been set to 1024 * 768 )

[manashpal]

After installing Debian latest Jessie in my system, I am getting a 1024*768 
screen resolution, but my monitor can render 1366*768. it is unlikely to have 
got such a unexpected screen resolution like 1024*768. on the other hand 
ubuntu, fedora, kali and many more linux distros has never disappoint me such a 
way. how can I fix it ? kindly let me know the steps I will 
follow.thanks.m@n@sh..........p@l