each product community has it's own Ideas section.
There is information about the new process at the following support site http://www.bmc.com/support/support-news/ideas_launch.html.
Also have a look at the document linked from that page http://media.cms.bmc.com/documents/BMC+Ideas+Overview.pdf.
It describes how to find the right community, create an idea, vote for ideas of other members and the stages of the submission process.
Hope this helps,
There is two way to file an RFE. One way is to create an idea here and have people vote for it. Secound way is to find the defect with support and post it here with the defect number.
For MainView and other BMC mainframe products, contact your Account Manager or Software Consultant they can help you submit a request for enhancement.