Hi i am planning on changing my brakes and my tires but i don't know what i have to buy for new brakes and what kind of tire should i look for? I will be doing a lot of tricks like a BMX is mean't for.

A picture of the bike would help determine what kind of brakes it has. Welcome to the site!

Thanks. I could post a picture tomorrow. I'm pretty sure everything is stock.

My bike is about 5 years old but it is extremely reliable and good.

The images are too big so here is a imgur album of the bike. Imgur: The most awesome images on the Internet

Kool Stop Salmon brake pads for the best stopping power. Any smooth tread tire in a 20X2.125 tire should be fine for local skate park or trick riding.

So these? https://amzn.to/24nI9TR I have 20 x 2.20 tires.

Good choice for brake pads. Either tire size will work. You can even go with a smaller size tire. Depends on your needs.

Ok i am fine with my tire size. Should i get anything else? Like a new chain since it was put to the test for a lot of years and also the bike was riden when it was raining snowing windy muddy basically the elements.

I think that chain can be cleaned up with an old rag and some oil with no problem. Single speed bike chains are pretty tough and don't wear as fast as multi-speed bikes. If you think you need a new chain and don't want to spend the time cleaning and lubing yours, you will need a new chain and a chain break tool and learn to measure and set the new chain length and use the master link. Youtube and Google are helpful tools on these matter too.

Ok thanks do you know how to tighten your pedals because when ever i pedal it feels loose since its really fast right when i push lightly on it and i like it a bit more tight.

Usually you tighten the pedals with 6mm allen key or a 17 mm wrench. It could be the cranks as well.