Dear Oasisji,
following are the basic exercise for a beginner which as you mention you are not ready yet to start with a gym yet. This exercise may be suitable for you as it is basic free hand exercise prior to joining a gym/weights workout. it cover each section of the major muscles, namely chest/pecs, back/lats, triceps, biceps, forearms, deltoids, thighs, calves and 6 packs/abs (abdominal). You may do for 3 months as free weights exercise and may add weights as you feel comfortable.( as "your self-image improve so shall yourself confidence"). You need a tape measurement, weight machine, a fix time to do exercise daily, your pullup(chinning) bar and a mirror.
the exercise: for beginner, do each exercise for 3 sets with 15 repetition for each one set. (3x15)
start with a warmup/stretching exercise. 10 mins.
Back: do the pullup/chinning up exercise. Hold the bar with palm over the bar, the wider the shoulder wide. this is to develop your lats/wings and back muscles. Do as many repetition (reps) as you can and bring your head above the bar. Repeat or work toward 5 times (sets). Between each sets take rest 45 seconds to 1 minute. do not take long rest, your body may cool down.
pecs/chest: do push up. flat with your palms slightly place wider than shoulder wide. feel comfortable. do the push up. work your way to 3 sets of 15 reps each. increase the set once you reach the goal. Only the chest touch the floor.
Triceps: do the dips. place 2 chairs with their back to each other. stand in between with your shoulder wide. push yourself up and this starting point. come down straight as possible with your legs bend at knee. your goal is to make the elbow parallel with the floor. this is to make your triceps mass. again do as many per reps per set with goal is 15x3. ( alternatively you could do by holding a bench with your palms and arms straight ( not total straight, bend a bit ) with your back and place your legs on another bench ( horizontal) lower your self and until your elbow parallel to floor.)
deltoids/shoulder: same as exercise but slightly bend forward , you will exercise the delts, pecs and triceps.
biceps: back to chinning bar: this time hold the bar with palm under the bar( underhand), hold it shoulder-wide, raise yourself up, do as many reps as you can for 3 sets with goal target of 3x15. this is to build your bicep overall mass.
forearm: just move your palm above bar with narrow grip on the bar( slightly lesser than shoulder-wide)
do as many as you can. (not necessarily 15x3). (caution: this exercise may tear your forearm muscle if overdo or not done properly and create soreness)
thighs: do squat. this exercise build mass for the thighs as it overall build both front and the back of the thighs. place your feet shoulder wide and come down with your thighs parallel to the floor. if you notice that you are leaning to front, then place a book or wood say about an inch under your heel. if the toe place slightly inward, then you are working out your outer thighs, if toe slightly outward then you are working more on the inner thighs. again work toward 15x3.
calves: place your toes on a higher platform so much so that when you stretch your heel below it does not touch the floor. raise the heel by using the calves muscles up. the toes remain in same position. do the up and down motion until you feel soreness in the calves. slightly inward toes workout the outer calves and vice versa. feel the stretch on the calves. the leg must be straights. a you feel comfortable with 15x3 later, you can place someone, a child, on your shoulder while doing this exercise as increasing the weights. (alternative with donkey-stand)
abs: leg raise for lower abs. crunches for upper abs . and twist with a broomstick for obliques/side abs muscle.
the above exercise will normally take about 45 minutes. you must do warm-up. do 3 times a week. on rest day do cardio exercise. do abs daily. if possible have a large mirror to monitor your movements and mirror is a best tool to be your critics. take measurement and record it. review weekly. you will see the results soon.
kindly consult your physician before starting any exercise. Darshan.