Info path software

Hi Masoud1313 

I would STRONGLY recommend that you start with SharePoint FIRST. There is a lot you can do with out of the box SharePoint. Like most things, the more out-of-the-box you can be, the better and more stable your product will be. Conversely, the more moving parts a thing has, the more places it has to break and the harder it will be to troubleshoot and fix when they do.

Beyond the basic column types, you'll definitely what to learn about content types as they will allow you create multiple "custom" forms for a list or library without the added trouble of actually customizing the forms. You'll also want to learn about calculated columns and formulas.

And there's a ton you can do with modern pages and list views to shape the user experience of your list or library.

Avoid Designer at all costs. It doesn't work with the modern sites, or at least not well and there's zero point in learning classic at this point.

Personally, I avoid customizing forms like the plague.  But if you absolutely MUST have a customized form. Like there's no other way around it, you understand it's an additional  layer of complication, and that you will be the permanent owner of this list and form because your users will NEVER learn it, then go with PowerApps or a 3rd party app like Nintex or K2. Make sure you document everything well because you won't remember it 8 mos from now.

Good thing every SharePoint site comes with a OneNote notebook! :-)

If you use PowerApps, make sure you understand the difference between a customized form and an app and the implications of choosing one over the other.