Combining standard and aside posts

Hello. I want to be able to post a mix of standard and aside posts in my legal news site. And for the life I cannot figure it out how.

The theme I am testing out states that it supports post formats. But it does not display the option to choose the post format on the right sidebar.

I am using the Advanced Excerpt plugin, but that’s doesn’t do what I really want to do. If I use the manual excerpt, I cannot format the text or include a link.

Your assistance would be appreciated. Thank you.