I am going to give you a quick introductory lesson on how to import and work with a point cloud file. First of all you need to open a scene to which you want to import the point cloud.
Go to File > Import > Cloud and choose your point cloud, in my case the file “hood.xyz”
Make your perspective window full size, then using ALT+SHIFT do a “Look at” to fit everything in the scene into view. If you do not have the View Panel then you might be using the View Cube. In which case you should click the little house icon next to the cube.
In order to better visualize the point cloud you can pick it using Pick > Cloud from the tools palette. Somehow clicking a point doesn’t work so well so I suggest you use a box select over a portion (or all) of the cloud, either method will select the entire cloud.
I am now seeing my point cloud (selected) as something like this