You want to make contact with your shoulder on the player's body between their thighs to their stomach. You put your face to the side of their legs, so that your cheek is on their butt. If you can move at a relatively fast pace moving in to the tackle, you can hit them hard, pushing them backwards and rolling them onto their back.
Think of something that makes you very mad!!!! Then go!! :)
Imagine you are just driving straight through them. Aim to stick a shoulder in their crotch, grab on knee, lift their foot off the floor and drive like hell. Get up asap and get ripping!
Keep very low hit very hard with your head in a safe position (not gonna get landed on), then wrap your arms firmly around player and drive through with your legs. Watch this video. Try to copy him but wrap your arms around more:
