For some reason I can't seem to check my mail on the iphone?

Can someone please explain this to me? I have an iphone 4, and I recently updated my iphone a week or two ago, and everything seemed okay until now. I can't seem to load up new e-mails.

Also, can someone please tell me how to set up a voicemail box? I can't seem to do so.

Go into phone - voice mail then custom greeting