Hi Sonu,
The steps to use "pubish" function are same for both MATLAB desktop and online versions. First you have to create a .m file and include all the content that you want in your published documentation and then you can just run "publish" function in the command window with the options that you want to use.
If this do not help you can share the exact error when you use MATLAB online so that I will be able to reproduce or rectify the error.
% Suppose you have a publish_file.m file that you want to publish
publish('publish_file', options);
For more information on "publish" function you can refer below documentation:
Hope it helps!
