No other dance connects two people more closely than the Argentine tango, emotionally as well as physically. Part of this is the dance position. You face in the same direction (the woman's right, the man's left) and so dance almost cheek to cheek. You also keep your arms around each other for the entire dance.
Take your partner (real or imaginary) in a standard dance position. Keeping your upper body straight, shift your weight onto the balls of your feet. This will push you and your partner very lightly together, helping weld you into a couple.
If you're a man, pull your partner toward you with your right hand behind her back. If you're a woman, place your left hand on your partner's upper arm just above his biceps and push against him. Both pull and push should be as gentle as you can make them and still remain firm.
Extend your other arm (the woman's right, the man's left) to the side in the usual ballroom manner. Do NOT let your arm sink like a lead weight, or flop around like wet spaghetti. Instead press very lightly against your partner's hand. During practice you may want to keep your "balance" hand flat against your partner's palm rather than clasp it. This way any lapse in pressure will cause your hands to slide apart, giving you instant feedback so you can quickly fix the problem.
It's a good idea to practice dancing with an imaginary partner with your arms and hands properly placed. This will strengthen your muscles and habits so that you can keep a good frame without thinking about it.
Now try walking in the Line of Dance with your (real or imaginary) partner, the man facing forward along the LOD, the woman backward. Do this first without music, trying just to keep a good connection with your partner. Keep your head up and turned slightly to the side, staying aware of your surroundings as well as your partner. Then turn so that the man can walk backward along the LOD, and the woman can walk forward along the LOD. Now walk some more.
Lastly, put on some music and walk around the room in time to the music. Try to do everything right that you've learned so far, but don't try too hard. Instead, concentrate on having fun. Because you're dancing, and learning to have a good time is also part of learning to dance!