Welcome Rachel,
this is good news! You will love to have a reader and wish you had bought one earlier. The reading is sooo nice with them!
Don't let jbcohen confuse you, of course you can buy books with Sony Reader Store for your Kobo or take advantage of their free books. The Kobo will read them just fine. It won't be able to read Amazon and B&N books as they have their own DRM. Everything else, as long as it is epub and not mobi will be fine with your device.
Please check out
the forums library and
deals and freebies for the latest books for free. You may also want to join
the Singapore Library that is for free and has a section of Childrens books. Just set up an account giving a 6 to 8 digit code of your choice or your passportno. and a name. Don't wait for their announced reply mail, it will never come and down-you-load
There is a
Kobo forum here you might find helpful, too.
Have fun!