new to the sport(only 12)
im only 12 and i ride around cheap walmart mtb. (im on my dads account)would the bike be ok for my age and for a beginner
Welcome to the sport! Anything is better than nothing! BUT...make sure to have someone who knows bikes make sure your Walmart bike is safe to ride. They are not usually assembled very well by Walmart employees who are paid a buck a bike and slap 'em together as fast as they can. A bike shop will probably charge you $30-60 to tune-up the bike and make sure it is assembled properly.
But having said that, start saving pennies from allowance, yard work, birthday gifts, etc. You'll be much happier on something from a bike shop, even if its "only" a $250-300 model. The bike will work ten times better and last 100 times longer.
And always wear a helmet! -- even if it's a cheap helmet from Walmart. The helmets at Walmart may not be the most comfortable, light, or ventilated, but they'll still protect your noggin.
good luck, and have fun!
You are probably growing so fast that you will outgrow bikes very fast. So, you won't have to worry too much about it lasting for many many years. I think as long as you are enjoying the bike that you have, it will be just fine for you for now. But, if you really like the sport, it wont hurt to keep saving up for another bike in the future.