I got two papers accepted and I am just wondering how to know their policy towards publishing my papers also on CoRR. is it fine to publish the same paper in CoRR and in the conference?
Normally, it's fine, as long as you submit a pre-print and not the camera ready of the conf proceedings. You can also check these questions: Does publishing a paper on arXiv prevent me from submitting it to a non-open access journal? and Submitting a subset of my work to ArXiv.
In addition to Charles's answer, it depends on how the conference papers are published. If they're published as a special issue of a journal, then it may very well depend on the policies of the journal, as well as those of the conference. (And some conferences may have special restrictions on publications; in those cases, you should check with the conference organizers.)