When you play the right note or chord, you will hear it. It will be a pleasant sound, it will be clear and won't have any blocked string sounds (unless it needs to, but you'll get to that later). To play a note or chord correctly, you have to get your fingers in the right position and press as hard as you can on the frets; it will become a habit if you practice enough.
If you are practicing regularly, like you should be (at least once a day) be sure to change your guitar strings once a month. You will be amazed at how much of a difference in sound quality a fresh pack of strings will make. You don’t need super expensive strings. When I was starting out, I got by quite happily on my local music store’s house brand of strings that cost about $4 a pack.
After teaching guitar and music theory to thousands of students over past three decades, I thought that I had basically 'seen it all' when it comes to guitar instruction. Then I discovered Justin’s website, and man was I impressed! Justin’s caring spirit, attention to detail, vast knowledge base, and especially his lucid, laidback and nurturing style, allow students to fall in love with the learning process. You see, it’s not enough to simply find out how to play a few cool licks or chords. A truly great teacher will make you fall in love with the process of discovery so that you can unlock the best within you. Justin is one of these great teachers, and I highly recommend justinguitar.com to anyone who wants to tap into their best selves.
Open up audio for the riff and follow the tabs. Open the song that you're covering in another window on your internet browser. Play through the song and trace the chords and notes with the tab that you looked up. Try to follow the numbers on the tab with the notes that are being played in the song. Try to get an understanding for which chords the artist is playing before trying to duplicating it.

Beginning Guitar Class - Open to all beginners age 13 and up, or intermediate players who want the review. Begins with holding and tuning your guitar, names of guitar parts, and quickly progresses to chords, scales, tabulature, and playing basic songs. A variety of styles are introduced to encourage students to explore and find the styles they like best. Classes are organized according to age and skill level, so it's an easy way to make new friends too. Classes start every month and may be repeated as often as you like. Cost is $70 per month (4 hours).