Many people already have. Do the legwork. Start w/ Mark Rippetoe's beginner program. Sadly, you may have to spend a few minutes researching to figure out what that is, but I assure you, it will be worth it.
As for your inability to do lower-body work, you can do deadlifts, sumo deadlifts, hack squats, jefferson lifts, olympic lifts, you can have a squat rack built fairly cheaply, you can deadlift the bar to your thighs, squat, hook your arms under the bar and do zercher squats, or you can clean the weight off the floor and do front squats.
You can also snatch the bar off the floor and do overhead squats. You can also do unweighted single-limb leg work. You can do lunges, reverse lunges, and walking lunges with your dumbbells. You can do dumbbell squats and dumbbell deadlifts. You can do dumbbell swings and dumbbell snatches. You can do dumbbell step-ups onto your bench. So I'd say you have plenty of options.