I use a great triceps exercise that not too many people are familiar with:
Lying flat on your back on a bench, holding a dumbbell in each hand so your palms next are to your pecs and are facing your head (as opposed to normal bench press, in which your palms are facing your feet).
Push the dumbbells straight upwards, but twist them inwards, so at the top of the exercise, your palms have rotated and are now in the normal bench position (facing your feet).
Rotate them while bringing the dumbbells back down, so you are in the same position you started in.
That's one full rep! I hope my explanation makes sense... I tried to search for an online photo to which to direct you, but I don't even know what this exercise is officially called!
It takes some getting used-to, and it may take a few tries to figure out what weight works best for the number of reps you wanna do (it'll be less than what you use for normal bench, I can tell you that much), but it's a great triceps exercise that also hits the shoulders, pecs, and forearms.
Good luck.
The exercises above are good ones to begin with. If you don't have a gym membership or dumbbells, you can use canned soup or bottles of water. If you don't have a bench, use a mat or folded blanket on the floor. The floor alone may be hard on the hip/pelvic bones or the back. Good luck.