You don’t need to join a gym for strength training. Your muscles don’t care where they are working, and they don’t even care if you are using dumbbells or soup cans. You can use free weights at home (or household products, such as soup cans). Personally, I like to use my TRX suspension trainer, my TRX Rip Trainer or my bodylastics resistance bands. All I need is an anchor point (a strong solid door will work just fine) and some room to work, and I can get in a full body workout without leaving the house.
If training is new for you, I’d recommend seeking the advice of a certified personal trainer to get you started with home workouts. Proper form is key to a safe and effective workout, and a trainer will help you with this.