Here are my corrections - I hope they help! Also remember, depending on where one is born, the style of English varies. I'm from the US, so this is how I would personally word this. I have bolded my notes that may possibly help you! ^_^

Hi Guys,

(Always make sure you capitalize the first letter of your sentence.)

These days I'm practicing English using South Park. ^^;;;

Is this not a good way? Any opinion is welcome. :)

I've watched movies or news mainly, but someone once recommended me to I watch some episodes because of they were about some of the issues we were talking about. 

(Now - the "I've watched movies or news mainly" is correct if you're using past tense. Meaning you viewed those in the past but not recently. If you're telling us that you watch them now (daily), then you would word it how I did in the red.)

And I realized there were many words in it I've collected and memorized from other materials.

(Here again "...I've collected to memorize from other materials." - did you collect the words to memorize in the future or have you memorized them already? If you simply collected them to memorize, the rest of your sentence is correct. However, if they are words you have already memorized, you would word it like I did in red.)

I can't say if it's a good material or not already to judge, but at least I'm enjoying it.

p.s You can also correct the sentences I just wrote ^^;

Thanks in advance, all :)

And there you have it! lol I hope that I have helped you a little! I'm definitely not be best at English/Grammar but I hope I'm not the worst keke ^^v