Hi Doug,
To add introtext to your blog post, if you currently using EasyBlog 5.0 builtin composer, you can place a 'readmore' block at where you want your text block to act as introtext
If you are using Joomla editor in EasyBlog, you can do the same by adding the readmore tag inside your blog post content
If you simply want to take the first few blocks from your blog content as display at introtext in blog post listing, when you can the setting at EasyBlog backend under settings -> layouts -> truncation.
Hope this help