Question 366456
I got a feeling you meant the following:
p(X=0)=.25,
P(X=1)=.125
P(X=2)=.125 and
P(X=3)=.5, right?
The cumulative distribution function is 
F(X = 0) = 0.25
F(X = 1) = 0.375
F(X = 2) = 0.5
F(X = 3) = 1.
It's easy to plot the probability mass function for this distribution.