The imperfect tense (l'imparfait), one of several past tenses in French, is used to describe states of being and habitual actions in the past as well as several idiomatic uses. Generally speaking, the imperfect describes past situations, while the passé composé narrates specific events. In addition, the imperfect can set the stage for an event expressed with the passé composé. The imperfect describes an ongoing action with no specified completion:

   J'allais en France. - I was going to France.

   Je visitais des monuments et prenais des photos. - I was visiting monuments and taking pictures

The passé composé expresses one or more events or actions that began and ended in the past:

   Je suis allé en France. - I went to France.

   J'ai visité des monuments et pris des photos. - I visited some monuments and took some pictures.

The imperfect is used for habitual or repeated actions, something that happened an uncounted number of times:

   Je voyageais en France tous les ans. - I traveled (used to travel) to France every year.

   Je visitais souvent le Louvre. - I often visited the Louvre.  http://french.about.com/od/grammar/a/pasttenses.htm
http://www.cliffsnotes.com/foreign-languages/french/french-ii/french-ii-past-tenses/the-imparfait
http://www.laits.utexas.edu/tex/gr/tap5.htmlhttp://www.laits.utexas.edu/tex/gr/tap6.html

Ne...Ja'mais-never      Je n'ai jamais fait ça.      
Ne...personne-nobody        Je ne connaisssais personne.
Ne...pas-not             Je n'ai pas.             
Ne...rein-nothing     Pendant le weekend je n'ai rein fait. 

It's so simple. All you do is hit the 'Alt' button on the left hand side of the keyboard, then type in the number code given on the chart.

This option is also simple, but a bit more time consuming. All you need to do for this one is click on the accent you want. You would then need to copy and paste it to your work where needed.

This final option is like the chart listed above, but it also comes with upper case letters, and some punctuation marks. It works the same as the chart, just hold down the 'Alt' key and type in the four digit code.