How can I change the text given on a Tumblr theme?

There was already a question about Tumblr Themes, but I still have a question. How do I change the text which is already displayed in the Tumblr Themes? I have choses this theme: Strict by arood. This is some of the text which comes along with the theme:
this is a tumblelog, kinda like a blog but with short-form, mixed-media posts with stuff I like. Scroll down a bit to start reading, or a bit more to read more about me.
8th November 2006

3,688 notes

A memorable quote
“
It does not matter how slow you go so long as you do not stop.
— Wisdom of Confucius
Tags: wisdom
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How can I adjust? I am really a novice when it comes to these sort of things. I need to change the text and put in my own.
Thanks for yr help in advance!