I Need Help

So i'm new to all this. All I can find through Google are just brief articles about all this and to be honest those felt like common sense.
I need something to get me started like a tutorial, but I know you guys are busy so you don't have to post links here or write a whole lot of explaining here if you don't feel like it. Just give me some keywords I need to know and I'll move on from there.

Now while you're reading this, there is this 1 question bothering me, correct me if there's something wrong with my logic:

Let's say I uploaded a video and it gets ranked somewhere on page 20 of my desired keyword, I use lots of optimization and it gets ranked on page 10. So how does SEO prove useful? No matter how hard I try it's not going to end up 1st or 2nd page from the 20th page. wouldn't all the optimizing that I've done becomes useless since people neither browse the 10th nor 20th page?

try on the video description Keyword , www.yourdomain.com
also build backlinks to you video , bookmark it , get traffic to it through social media , and keep on building backlinks .

Thanks d4l1t0s, anyway I browsed through the forums and kind of figure out how newbies are supposed to learn things - search function+ observe.

But I still hope someone will answer my question.