So I'm making glasses because that's what I decided to make (still learning so making simple objects) and ran into this problem. I have no clue how to put these vertices (I think they're called) onto the edge here. Is there any way to merge, or weld them onto it?
Add another edge loop in the crossbar piece (the top of the glasses) and move that edge loop near the vertices you are trying to join. So you'll something like this
| | | *-----------*---------* *-* | |
| | | | *----------*-*---------* *-* | |
For more on adding loop cuts, click here
Then merge the vertices using Alt+M.
Which becomes this:
| | | | *----------*-*---------* | |
For more on merging : click here