Hi sidhanta,
To clarify, you are trying to add a Content Editor Web Part and an InfoPath Form Web Part to a single Web Part page?
Are you getting any errors/feedback? I am able to do this with no issues using SharePoint 2010 and InfoPath 2010; in fact, on one page I have 2 InfoPath Form Web Parts with 3 Content Editors... I just clicked on the Edit Page button, then on the "Add Web Part" box on the page and I was able to add each Web Part normally. This is out-of-box functionality I believe.