To filter by campaign or ad group in Analytics, simply navigate to the campaign/ad group filter at the top of the screen and start typing the names of the campaigns or ad groups you'd like to restrict your search to and hit enter or click on the entry.  

To remove them, click the "x" at the right of the campaign name or hit backspace if your cursor is in the search box.

For metrics filters, click the filter button at the top right of the analytics table, set up the filter you want, then click "Add"