Magento 2.2.3 custom payment gateway building

[bbbmishucs]

I am working to build up a payment gateway where I've to pass some info like orderID, Amount and SessionData to a bank's payment gateway. 

Bank provide me the API demo of pure PHP files where Marchant credentials are have been set. 

Now I want to build a payment module of that Bank. How can I do that in magento 2.2.3? 

Best possible answer I found in stackoverflow. 

here is the link below:

How to post data to a payment provider when placing an order in Magento 2

I've the similar problem for my query.

How can I use form-building and custom url to transfer store data to bank api and then after payment redirect customer to my site? Can anyone explain?

But I don't understand the answer fully and It seems complex to me. Can you please suggest me a better way? 

[Dhiren Vasoya]

You need to read this article.
So you get the idea.

https://magecomp.com/blog/create-custom-payment-method-in-magento-2/