I have just be introducted to Cryptocurrency and I would like to ask some questions

I have taken out time to study about bitcoins, the pros and cons, the Investment schemes around it,but i not being able to get some right answers.

So, the following are some questions I want to ask about cryptocurrency

1. What is bitcoin?
2. How can I use the withdrew my fund from Steemit ?
3. How can I be more active on Steemit platform ?
4. Why should i invest in Cryptocurrency?
   

I hope that with the knowledge share with me will help me become better investors and user of Bitcoins.