Upload excel spread to forum for guide?

Sorry I am a bit of a noob when it comes to forums and how they work entirely. I was wanting to figure out how to properly upload an excel spreadsheet to the forum in order to keep its formats.

I have created an in-depth guide to a key element in the game that can benefit many, just need to know how to load it up to make it understandable.

Figured this would be the best place to ask considered the off topic subject but hey a flip of the coin decided beginners.

If anyone understands the nature of the question and has a solution please respond.