Where Do We Report SharePoint Online Bugs?

I just need to know the proper place to report SharePoint Online bugs to Microsoft.

I've found a couple:

One when setting up a Site Mailbox, after selecting Language and Time Zone, I get, "The custom error module does not recognize this error.". (Might be because Outlook isn't set up yet, but I wish the error said that.)

The other is in the OOB Issue List. I tried changing Category from dropdown to checkboxes and the error is, "Non-supported field type change. The field cannot be changed to the new type. Please check the new type and try again.".