Tajweed is about reciting the Quran. there are many different ways of reciting the Quran; as the Quran was revealed in many different dialect but only a few survived until out time.

I do not actually know what the word "tajweed" means literally.

Usually the first thing you (should) learn in tajweed is the articulation points of the letter, but you might find excruciatingly boring to read and it would be better learnt face to face or at least orally with a teacher.

To improve your tajweed i would advice practicing reading the Quran with Khalil al-Hussary. HE reads slowly mashaaAllah.
method: listen to an ayah, repeat until you get it kinda right/you forgot what is sounded like; listen again, repeat until you get it right; listen again if you want.

i advice doing it ayah by ayah.

Tajweed pointers/reminders

full letters: khaa, raa, saad, daad, Taa, Thaa, ghain, qaaf.

these letters you pronounce full, aka: you pronounce them as if your mouth was full, what is suppose to happen is that the BACK of your tongue rises, this is how you make a letter full.
raising ONLY the back of the tongue requires practice. I advice the use of a mirror. I'm serious.