How do I connect the vertical part of my railing to the angled part? I was wondering if there was a way to do this without just eyeballing it. They are both part of the same object.
You may use the knife project tool. Duplicate the top face of the vertical cube (Shift+D), place it between two cubes, then separate the face (P). In Object Mode select the newly created plane, then the angled cube and press Tab to enter the its Edit Mode. Go to the bottom view, press Spacebar and type Knife Project. Delete the plane. Join objects with Ctrl+J. Join meshes in Edit Mode using Bridge Edge Loops operation. Finally dissolve the horizontal edge with X-->Dissolve Edges.
I don't know of blender easy tools to do that, there is a way using booleans, but if you need a simpler solution, I can't help. Also, I suppose you just need to "snap" the vertical bar top face to the upper bar, not create a connected geometry from the two separate meshes.
Here is the method I said above: in this case, starting from this
I would go to side ortho view, and duplicate the vertical bar,
then either move or extrude this copy until it crosses the upper bar, and also scale this copy over X axis (eg: try scaling just a little down over X)
Then, apply to copy mesh a boolean with intersect to the upper bar (the scale over X we made before now helps the boolean), and apply.
This creates vertices in the copy mesh that may be later used to snap the original vertical bar vertices (extended or extruded).
After extending or extruding the top vertices of the vertical bar, snapping them to the copy mesh vertices, which are exactly at the intersection you need,
you can then delete the copy mesh.