According to my experience and research, I would suggest you go for online Selenium Training by Intellipaat, they are the best who provides online Selenium training. You can get the industry acceptable Certificate by Intellipaat and moreover, this course is being taught by experienced Trainers, so ultimately you will get a great knowledge of Selenium.
Let's know something about Selenium:-
Talking about Selenium, it is an open-source automation tool that is used for automating Web Applications. This Selenium training course will teach you how to work with Data Driven Framework and Keyword Driven Framework and perform Cross-browser testing. You will also get to know about Selenium IDE, Selenium RC, Selenium WebDriver and Selenium-Grid during the course. One of the important things that, you will learn is to perform tests on multiple machines simultaneously running on different Operating Systems, integrate other frameworks like JUnit and TestNG with Selenium.
You can learn more on Selenium from here:-
Selenium Tutorial- Selenium Tutorial – Learn Selenium from Experts.
Selenium Interview Questions - Selenium Interview Questions and Answers.
Here is also a Selenium video tutorial which you can watch to learn it in a much better way.