To add a new blog post, start from the admin or edit mode for your chapter website. Click on + New and then Post. This will add your new content to the Blog page. Be sure to Publish the post when ready.
You can also edit your post by opening the blog post and then clicking Edit Post in the upper menu.
To add an image to your site. You need to upload an image to your Media Library and then add it as the Featured image. Here is the Astra Theme page to help with Featured Images – wpastra.com/docs/recommended-featured-image-size.
Reach out to doug.agee@tu.org if you have questions about adding blog posts. The Astra Knowledge Base has a resource for getting started at wpastra.com/blogging/first-blog-post.