By default blog posts are in reverse chronological order. The most recent post is on the top of the list and a new post pushes the list down. Normally this is what you want and it is the natural order for a continuous blog.
But if you want to write a blog documenting a vacation or trip you have taken, or if you want to tell a story, it might be better for your readers to start at the beginning and work their way down the list.
In other words, somehow you need to change the natural blog posts order from reverse chronological order to chronological.
The way you accomplish this is to change the date or time of the posts manually.
Blog posts are time-stamped automatically when you publish them. You can see the dates in the list of all your posts.
To change the date you click on the post to edit it. On the right side you will see a section called "Published on" where it shows the date and time that you last published the post.
If you click on that it will expand to allow you to enter a date and time manually.
You want to select a date and time and make a note of it. In your list of posts you want the dates or times to be sequential. So for each post you need to make the dates or just the times sequential. I usually make the date consistent and then add an hour to the time for each post.