Hey everyone, i got an Ideal Boommax mountain bike (info below) and i want to sort out all the little problems. The suspension, front disk brakes, and gears are the main things i need to look at. The disk brake is not as good as it should be, the gears aren't changing properly, and i have no idea how to do the suspension. Can someone please explain how to maintain these things, in simple terms?

Kinesis alloy 6061 frame
RST321-CL 63mm suspension forks
Altus rear derailleur
21 Speed Shimano E-Z fire gears
Joytech alloy hubs
Promax Disc hub alloy quick release & mechanical disc front
Promax alloy V-brake rear

Thanx for any help, greatly appreciated.