I made an account on kobo, then bought a book, but then i have no idea what to press to read it, when i go there it says ''you already own this title, write a review or view in my books'' i go to view in my books and it brings up the book, if i press on the picture it goes back to the start, if i press on the name under the picture it goes to the start, i am not sure how to start reading the book.
There are several things you will need to know about ebooks, if you intend to buy more.
To read your ebook you need an ebook reader which may be an independent piece of harware, or an app running on your smartphone, tablet, or computer. It must be able to read ebooks in ePUB format, which is the format used by most vendors, Amazon excepted. Hence, nothing from Amazon will work for your book (which is not a problem).
Now things depend on how you want to read the book. I assume you do not own a hardware ebook reader device.
Then the simplest is to download a reading App from Kobo, on the device you intend to use for reading. For that, simply log into your Kobo account, then go back to the page where you bought the book (or any other page to buy a book) and click on "APPS & eREADERS" on the second line of the page. Then it is up to you to decide on what you wish to install, and where from the diverse possibilities made available by Kobo.
I never used this software (I use a Kobo hardware reader device, and also Calibre, which is an independant free software app with lots of tools, and working on more computer platforms) so I am not sure about the following steps, but I expect you will get instructions from the Kobo site. Most likely, if you are logged in your kobo account, books will be automatically downloaded to the reading application.
It may also be possible to read ebooks directly with you web browser. For example, Firefox has an EPUBReader extension for reading ePUB books directly from the web, or from your files. If you use such an extension, it will be called automatically to open the book whenever you try to download an ePUB file.
Some tools may not work for books that have DRM (digital rights management). But DRM is a hassle for many things, and I personally try to avoid books with DRM. Apps from the vendor will usually handle the kind of DRM used by that vendor, but these apps may not work on all platforms.
As you see, there is a large variety of ways to do things, with also a variety of pitfalls. Some of the answers depends on your platform (computer and operating system) since you seem to want to read from your computer. But you did not give precise information on that, so that it is hard to answer more precisely.