Losing weight, get yo diet straight. Exercise is important, but it won't get you where you wanna be if you don't have a proper diet. So sort that out.
Okay, so I'll just tell you what I do and open myself to criticism from the experds here (which I look forward to). When you get a programme someone else gives you, eventually you learn what's good for you and you tweak it to suit.
Day 1: Chest & Tri; Day 2: Back & Shoulders; Day 3: Legs & Bi
* when I do 4 sets, they are usually sets of 12, then 10, then 8, 6... or until failure. Others say do 3 sets with higher intensity, but I like it this way.
** as you're now starting, the volume below may be too great, so don't overwork yourself, and don't so much that would discourage from going back. Also, get your form straight before looking to go heavy. SOme exercises, form is more critical or you can injure yourself easily: squats, bench presses.
You can this website to see what exercises you can do for each specific muscle, and there are gifs to show how you to do them -
http://exrx.net/Lists/Directory.html
Chest: 4 sets flat bench press, 4 sets incline press, 4 sets dumbbell pullover, 4 sets incline dumbbell press, 4 sets of dips (if you can't do up to 12, do until failure)
This routine may be repetitive and over focus on upper chest but I feel that I may have been overdeveloping lower, so now I'm compensating.
Tri: 4 sets kickbacks, 4 sets lying tricep extension, 4 sets cable pushdown
Back: 4 wide grip chin ups, 4 front pulldown, 4 seated high row, 4 bent-over dumbbell rows, 4 hyperextension
Shoulders: 4 dumbbell shoulder presses, 4 lateral raises, 4 rear lateral raise, 4 front raise, 4 seated reverse fly, 4 upright row
Legs: 4 squats, 4 loaded leg press, 4 lunges, 4 leg extension (gonna do away with, apparently is bad for your knees), 4 hamstring curls, 4 seated hip adduction, 4 standing calf raises, 4 seated calf raise with plates (not sure what it's called)
Bi: 4 dumbbell curls, 4 barbell curls, 4 hammer curls