How to Macro with 1 Excel with 40 tabs / sheets?

[caltang]

I have 1 Excel file, but it has 40 tabs / sheets. 

Each tab / sheet has around 4 columns, but they are not consistent throughout the 40 tabs / sheets in terms of column position.

How do I dynamically import them with a macro? I can't seem to get my macros working at all.

[caltang]

Thank you @FilipR ! 

I will study it in more detail, but so far this works for me.

Thank you!