#1
Hi guys I'm new here. I'm practicing fingerstyle guitar and I want to know how to play this,by strumming or what? What does x means too and how to play it. Sorry for my bad english. Thanks in advance!
#2
An X is pretty much just a muted note. You really shouldn't over think it. The person who wrote the tab didn't really have to put those in this case I believe. In this case it basically means those strings aren't played or they're muted. 

Sometimes certain songs have muted notes like this where its more important to playing the song. But in the tab you posted, it doesn't really matter as much. It just basically means don't play those strings with the X.

https://tabs.ultimate-guitar.com/s/system_of_a_down/war_tab.htm