"on your theme page it says not to take the credit out of the index page. what is the meaning of "index page"?"

the index page is the first page you see when you enter a blog, and not any other page like the permalink page or an about page or whatever has something written after “http://[yoururl].tumblr.com/”. basically the page with all the posts, your blog’s main page

"hellu! may i ask how you changed the text (... reblogged from; ... liked) to japanese? ive tried a lot already but i just cant seem to figure it out. thank you!"

hii you have to change the language of your blog to Japanese! for that go in the settings section (click that gear wheel at the top of your dashboard)