Hi Fellow Trailblazers!

I started to learn Salesforce in Trailhead a while ago and everything on the admin side seems to be understandable and no problem with the challanges. But even in the developer beginning trail there are certain modules that make me truly stuggle. And the Apex! I think I need to learn more about the basics even before starting any challenges. So where should I start? Is there any free materials for newbies? 

Hi,
Though i have coded the with the same specification as asked in the challenge but then also challenge failing.
Not sure why this is happening. The issue is actually the code or Trailhead is not working fine.

I am a beginner so facing issue in identifying it.
Need help.

Thanks in advance.