G&G-Fan wrote
I can't because I open it with Notepad on my computer.
OK. It seems you missed the install step. Downloading and extracting is not enough; there are a few more operations needed. Please, refer to the
installation guide for how to setup DokuWiki.
If you plan a local install on your computer, and since you apparently use windows, It's probably a good idea to re-download DokuWiki with the bundled micro apache web server (check the check box at the bottom of DW
download page).