I am also very new to vim, but I have a work-around for you (I think).
What worked on my machine is the following.
We start with the line:
first second third
Then in normal mode go to 's' of second and
yw (to copy this word). Then go to 't' of third and delete the word with
dw. Then use the last yanked text with
"0P. Note the capital 'P', so that the yanked word is placed before the next.
(found this last part here: https://stackoverflow.com/questions/54255/in-vim-is-there-a-way-to-delete-without-putting-text-in-the-register).
My first google hit showed me this:
The solution that is used there (and better than my own solution in my opinion) is:
1 "This first word should overwrite the second"
yiw yank inner word (copy word under cursor, say "first").
... Move the cursor to another word (say "second").
viwp select "second", then replace it with "first".
Is this what you wanted to do?