I hope you have installed the "robotframework-selenium2library". if not, please use the following pip command
pip install robotframework-selenium2library
I have referred your image and I could see there is a syntax error while you import a library.
In Robot test file settings sections, while importing a library the syntax should be
Library YouDesiredLibrary
In this case it is
Library Selenium2Library
Once you are done with all the imports you have the define any variables you want to use for your test case which you have done correctly.
In the test cases Table/section
You need to call open the URL, you need to user Open Browser keyword with browser name and URL ans arguments
Please try this and let me know.