Switching from Pilcrow to Twenty-Eleven Theme Problems

I’m a newbie, so this may be a silly question. When I switch to the twenty-eleven theme from Pilcrow and activate it. It loses the header, the menu and the sidebars, the colors and all design. It doesn’t look anything like the preview. I reverted back to Pilcrow, but like the drop-down menu options among other things for the 2011 theme (looks great in the preview). Is there a way to maintain all the design elements, sidebar, widgets and menu? Thanks. https://www.nourishedhealth.com