SharePoint 2013 web front-end URL Load balancing

Hello 

I have SharePoint 2013 Farm that contains the following servers:

1-   SPWFEI  (Web frontend I )

2-   SPWFEII  (Web frontend II )

3-   SPASI  (Application Server I)

4-   SPASII  (Application Server II)

How to create web application URL (for examplehttp://SP2013/) that I can access from SPWFEI and SPWFEII. And if one of two web frontends stopped… how to ensure the web application is working

Thanks,