I saw this question 12 hours ago and decided not to answer since the OP did not demonstrate much initiative -- especially given cfr's comment. The tikz manual is really easy to read and the commands fairly intuitive, so the OP should be able to at least start the question by themselves.
On the other hand, Torbjørn says that not everyone is familiar with the notation. So, here is a quick "tutorial" solution that does not answer the full question but gives the OP all that they need to be able to do it themselves:
\shade[ball color=blue](0,0) circle(2mm);% draw a ball at position (0,0)
\shade[ball color=blue](60:1cm) circle(2mm);% draw ball with polar coords
\draw[blue,thick](0,0)--(60:1cm);% a line between the balls
The only parts of this MWE that is not completely obvious is that
(60:1cm) is a polar coordinate with angle
60 degrees and distance
1cm from the origin.
Here is the output: