Create your project file.
Let's say you need a table. Goto table page of your library file and copy all table elements and variants.
Paste the copied stuffs to your project's component page, i.e., table.
Copy an instance of the local table to your working page.
If needed, modify the local table components with your custom content.
To add more columns
Select the header rows
Goto main component
Copy table head and paste ctrl+c/ctrl+v
To replace a text cell with custom cell
Create a custom cell, e.g., MyTable/MyCell
Select the text cell, select another instance in property menu: local/workingpage/MyTable/MyCell
To Clone the finally modified row
Detach a row
Copy the modified row
Right click the detached row, paste to replace
