I have LM LinuxMint 17.1 with LibreOfficeWriter. I like it, but I need to see how I can underline or do bold print in my documents.

I have clicked on everything, but I still don't see how to do it.

Any tips will be appreciated.

To the right of the font size window are three letters "A". Those are the features you are looking for. Highlight the text you want formatted and click on the relevant one.
:-)

Alternatively, to put text in bold, select the word, the sentence or the paragraph, and press CTRL b.
To underline a word, a sentence or a paragraph, select it and press CTRL u.