Cool that simpo is showing up :)
From personal experience, I have seen ghost when I was 9 years
old and living in a rented (very ulu) house for 9 months. Thank
goodness it was only for 9 months.
It was a white/black shadowy figure, I can only see the hand
clearly and it was sort of reaching out to me. I freaked out
needless to say, I was too shocked to even speak or move.
Later I got a sense that it was trying to seek help, I told my
mother and she helped donate money to dharma publishing in the name
of the spirits. They didn't disturb me after that and my mom said
on that day we were leaving that house, the whole house is very
smokey and they were probably trying to say thanks.
If you know of a Buddhist master who can 超度 the spirits so that
they can be reborn in higher realms, that is best and you can
invite him/her to your house.
Otherwise you can just donate money, or attend a puja (fa hui)
and dedicate the merits in the name of the spirit.
You should tell the spirit before hand in the house: I am going
to dedicate the merit of this deed in your name, please accept this
deed being done in your name.
IF the spirits keep disturbing you for some reason (usually it
won't be the case), there are ways like burning guggulu/guggul in
your house. As Loppon Namdrol says, that's one simple way to ward
off spirits. I'm not sure where you can buy them but they should
not be expensive.
p.s. dedication of merits is an effective way for lower realm
beings to attain a more favourable rebirth: http://www.jenchen.org.sg/vol5no1a.htm