Accute accent: Think mini forward slash above the letter. e.g. (é Hold Alt key and type 0233) Grave accent (Pronounced grav): Think mini backslash above the letter. e.g. (è Hold Alt key and type 0232).
If you are using a Windows PC, you will find a plethora of character shortcuts on an app called 'Character Map'. On Android phones you can hold the key until a selection of other characters appear.
I can remember holding down the Option key and double-clicking E to get é on the MacBook, but I'm not sure about iPhones.
Thank you very much but my question was more in the line of why and how does italian use the accents.
I used to think that they only used the grave for marking the stressed syllable at the end of words (that is the syllable which is said with more emphasis, like ca in cane).
I guess I should rephrase it as why do they use them. Is there a difference in prononciation or is it merely an orthographical convention?
A very insightful question indeed. Here is how I have understood it. The grave accent can appear on all five vowels whereas the acute accent only appears on 'e'. The function is the same for both - to place stress on the syllable. The difference is the way the 'e' is pronounced. The grave accent generally is used on 'e's that have an open mid-front enunciation (/ɛ/, as in caffè) whereas the ones with the acute have a closed mid-front enunciation (/e/, as in né). 'o' has this phonetic distinction too, but it seems that they've since stuck with using the grave for both cases.
Another good question. Short answer - no, it can also occur in unaccented 'e'. Hope this page helps you: http://italian.stackexchange.com/questions/1464/pronounce-e-like-%C9%9B-or-e.