You can truncate your blog entries so that only the first part of certain posts is displayed on the home and archive pages. When you do this, a link will be placed directly after your excerpt, pointing the reader to the full post.
Using the More tag
Go to Posts -> Add New in your dashboard to create a new blog entry.
Begin writing your post. When you decide that you want to cut it off, insert the More tag to split the post. You will see the More Tag as such in the visual editor
Finish writing your post.
Publish the post and view the front page of your blog. You should see your post effectively split using the More Tag.