Bulb mode on Nikon D90 and it's accessories?

Hi
I'm a newbie to both photography and this Forum!
I wanted some help with the bulb mode on my nikon d90
last night i tried to take a long exposure shot from sky, but i wouldn't exceed more than 30 seconds. For over 30 second shots, i had to keep my finger on shutter button and THAT WAS EXHAUSTING!
is there any way that i can keep the shutter held for more than 30 seconds without any remote or my finger being involved?

p.s.: can i use Nikon ML-L3 remote or Amazon wireless remote in these situations? Or only MC-DC2 remote can hold the shutter?

p.s. 2: sorry for my bad english!

A shutter release with lock is what you need.

The MC-DC2 would be my preferred option over a wireless one.

You might be able to save money and get a cheaper 3rd party one e.g. Hama

You need a tripod and a remote release - to lock the shutter open in bulb mode. The ML-L3 remote will do.