How is the educational system in Sweden??

See a translation

Big question, let me give you a rundown of the 'common' path people take. Note that there are always exceptions.
At age 6-7 kids start their 9 years of mandatory education. After that there is an optional 3-4 more years at a program more specialized to your interests. This will probably also be mandatory soon. Most people choose to go this way.
After that, if you're interested in studying more, you can apply to higher education at a university/institution. From there on the education system pretty much follows the same structure as a lot of other countries with bachelor/masters/graduate programs etc.
Without a doubt the best part of all of this is that the education at all these stages is paid by taxes, so in a sense the education is 'free'. You don't need rich parents or scholarships to get a good education. It's all up to you.