I am new to catia and I need to learn catia from basics from where I should learn?

The best way to learn CATIA to take an instructor-led class or two. And make sure the instructor is certified to teach CATIA.

The first you have to start with sketching parts. Make sure you have to take complicated sketches so that afterwards when you shift towards 3D it becomes easy to understand 3D model.

Hi
Best way to learn catia
First u should tool knowledge are follow
1.Sketch
2.Part model
3.Wire frame
4.Generative shape design
5.Drafting
U can go one by one, i said on above sequence
What u want, u can search in google or you tube, will get tutorial to learn

Dude, Catia is money eating machine, Catia instructors are not cheap, hence here is my 2 cents on it:
Install FreeCad, is a Catia like machine, but free, however it takes loads of computer power and resources, just like Catia, hence make sure you run it on a good machine, or it will not run well if at all, juts like Catia.

Follow tutorials, and ask questions online, and when you are good at FreeCad, you are decent in Catia and or Inventor too, same structure, same tools with different names (In Inventor is Extrude, in FreeCad is Pan) etc.