sharing folder over a network so I can access to it from multiple PCs?

That is the correct tutorial. It does not matter if lan or wifi provided all pcs are on the same ip address subnet (all IP numbers same except final number)

e.g. 192.168.1.xx

frozensun said:

I hope they are,will check later.
They all connect to internet over same router.
On the link above there are many Options 1,2...5 which one should I go for as the most easiest and fastest?

Easiest and Fastest might be mutually exclusive.

I would use Option 1 as it leads you through all key steps.

Just work carefully though the tutorial. If all devices are Win 10 DO NOT enable SMB1.

It's tedious, and it may take a couple of times through. Be prepared for frustration- or you might get lucky. MS has not made this simple and quick.

frozensun said:

Okay.
How can I check if they share same IP adress,or no need to since they all connect to same router?

Usually no need but you can check IP settings in network menus on each pc. They would only be different in special cases e.g. if one pc is a hyper-v virtual machine using default network switch.

Normally IPs are assigned automatically, but sometimes a user has set static IPs, and if set wrong, you can get issues. This is quite rare.

Rates for different Wifi protocols:
Different Wi-Fi Protocols and Data Rates

To find which one you're using:
How to tell which standard of WiFi I'm using - Quora

frozensun said:

Ok guys will try later.
All PCs are on W10 though PC 1 is connecting over WiFi dunno if that matters.
I'm curious to know what would be my transfer/copy speed in MB/s since I want to transfer large folders (above 20 GB)?

Hard to say as many factors. At top speed with a 1 Megabit wifi adapter, you can get maybe 1 GB every 5 seconds but could be a lot slower e.g. if using HDD rather than SDD maybe 1 GB per minute.

It also depends on how many files. Lots of small files are much slower than a few large files.