Dependant Drop Down Lists Help

Hi I am trying to create 2 drop down lists dependent on 1 column( a drop down list too).
Its like a mini sales pipeline thing
So 1st drop down is vendors, 2nd is Product ( dependent on Vendor), 3rd is Task ( dependent on Vendor too)
I am unable to attach file on both chrome and firefox.
So what I did is on a separate sheet I created table
Vendor1 Vendor 2 vendor3
Product A Product B Product c

Similarly on another sheet another table but instead of product , I put task

I can do only drop down for Vendor and Product but not for tasks using Indirect Substitute method.
Any help is appreciated. Thank you

Thank you for this. problem is I'm not understanding how to do this while on separate sheets.I saw multiple videos and i saw the tutorials and I saw the example but not sure how to do it right

Could you please help me. I have read through tutorials and videos and feeling more confused. I feel the best method for my case is Index and match but data validation doesn't work.
I used the one below. I have attached the new file that I am working on.I really appreciate help on this.

=INDEX(Tasks!$A$2:$F$25,MATCH(Demo!A2,Products!$A$1:$F$1,0)

Thank you for this. It is very helpful, but I am still facing trouble with it. For some reason, 2 of my vendors work when selecting major and task but does not for the others though the validation and naming convention is similar. Could you take a look at it for me as I intend to load a big list of vendors.
Thanks