Hi @andre62,
the way the steem blockchain works has changed significantly since I made that post. Unfortunately, steem is no longer mined that way.

If you are interested in "mining" steem now, you will need to become a witness. Click here for a good post on the subject.

If you are interested in mining other cryptocurrencies using the down time of your computer (yes, you will need to leave it on all the time), then you could start here.

There are typically two types of mining, CPU mining and GPU mining. The most famous currency to mine using CPU is bitcoin. There are a lot more currencies to mine using your Graphics Card (GPU). If you start with Ethereum, it's very simple to switch to different cryptocurrencies if you feel you want to change.

I hope that leads you in the right direction.