hold alt and press 0233 on the number bad on the right for an acute accent over an "e"
Go to 'Insert' at the top of your typed document, then click 'Symbol', and search through the box for your desired symbol.
If you have a Mac, then simply press opt.+e. A higlighted ´ should appear. Then press whatever vowel you wish to have under it. If you have Windows, sorry, I can't halep you.
Just copy and paste this - ü
Hold down Alt Gr, which is to the right of the space bar, then press I.