I want to become android and web developer , yes both . form where should I start?

I already know HTML and some basic CSS .

With the fcc curriculum is a good start, learn.freecodecamp.org

The first certificate is about html and css, with some projects to complete to get the certificate (you can go directly to the projects just to see if you can do them)

The others are about other things of web development

Should I complete FCC all tasks first ?

If you are confident with your html and css there is no need (the only thing you need to do to get the certificate is do the projects)

For the other certificates if you don’t know the material doing the challenges is a really good idea

so should I go for android now ?

FreeCodeCamp is for web development

Html and css are a small part of web development, with the other certificates you can learn other things

If you know only html and css you need to learn some more