You'll see the "Custom Set Creation and Discussion" subforum at the top of the card creation section is where you will want to share it. There are a few different ways to format, but it will take some work on your part translating from your current format.
If you can download a program like Magic Set Editor, you can plug all your cards into there, which you can then export through the program into either a PDF with card images or a text file that will be pasteable into the forums.
What is the best way to share my work?
At the moment it is just an Excel spreadsheet.
I have spent lot of time to create it so I really want to share it best possible way.
I have also created a quite simple formula to balance cards.
You'll see the "Custom Set Creation and Discussion" subforum at the top of the card creation section is where you will want to share it. There are a few different ways to format, but it will take some work on your part translating from your current format.
If you can download a program like Magic Set Editor, you can plug all your cards into there, which you can then export through the program into either a PDF with card images or a text file that will be pasteable into the forums.