It depends on the terms of your agreement. The general position is that authors are free to post the pre-print (version before peer-review) but not the post-print/publisher pdf version (version after peer-review). Some publishers however permit that the post-print be posted. So you need to take a look at your agreement and if in doubt simply put up your pre-print only. You may want to see Sherpa Romeo for more information: http://www.sherpa.ac.uk/romeoinfo.html
If you upload the published version - with the journal's style - then you have violated the copyright rules, unless you or your employer have paid the open access fee. What is much more preferable is to upload your last technical report from your institute, because that is not a violation of the copyright rules.
Every journal is different. Many allow you to upload your own "pre-press" original version, i.e. not their version with page numbers, etc. But some do NOT.
You must read their instructions to authors concerning copyright to see what the journal allows.
If you have signed the copyrights agreement with the publisher, and the paper is relatively new, then you cannot upload its published full text version. The best thing to do is to upload the rough draft of the paper. It is not the edited journal version, but still, one could learn from it a lot.
It depends on the terms of your agreement. The general position is that authors are free to post the pre-print (version before peer-review) but not the post-print/publisher pdf version (version after peer-review). Some publishers however permit that the post-print be posted. So you need to take a look at your agreement and if in doubt simply put up your pre-print only. You may want to see Sherpa Romeo for more information: http://www.sherpa.ac.uk/romeoinfo.html
Please check the University of California Open Access Policies page: http://osc.universityofcalifornia.edu/open-access-policy. You should also contact the UC Office of Scholarly Communication for advice on what you can and cannot do: http://osc.universityofcalifornia.edu/open-access-policy/oa-contacts/.
I would like to echo Most of what Kunle Ola has written above. Crucial is that you look at the "consent to publish form" you may have signed with the journal/publisher, in particular if it is not an OA article. http://www.allrightsonline.com
As long as the Journal is open access, there is almost no problem. For other journals you can also consult the Sherpa/Romeo model accessible at http://www.sherpa.ac.uk/romeo/definitions.php?la=en&fIDnum=|&mode=simple&version=
I think u can store the copyrighted article in ur institution or ur self website. This is general norm. However, the OA resources, there is no worry at all