I'd like to learn #WebGIS

[EhabAboassy]

I'm specialist in ArcGIS
I'd like to learn #WebGIS
What are the tools and software and platforms I have to learn to achieve this
Thanks for your advice

[JayantaPoddar]

You could get started with ArcGIS Online.

Learning Plan: ArcGIS Online Fundamentals 

Learning Plan: Make and Share Web Maps in ArcGIS Online 

If your organization is under Maintenance or you have an ArcGIS for Personal Use license, you could get access to the courses that requires maintenance.

You may further explore Learn ArcGIS and Esri's MOOC Program for more content.

Here is another list of references ArcGIS 4: Sharing Content on the Web - Course Resources