Often when words are expressing about time, they come in the "a case" with two fathas, this is because their function is like that of an adverb.

Some examples are:
قريبا
soon
سابقاً
previously
زمنا
for some time/for a long time
طويلا
for a long time

A point to note about these example words is that they should not be placed at the start of a sentence, rather they are suited to go at the end or later in a sentence.

Another useful word about time is مدّة
which means a length of time/period. It can be used vaguely for example:

بقي هنا مدّةّ طويلة
he stayed here for a long period of time

or more specifically, for example:
بقي هنا لمدّة سنة
he stayed here for a period of one year

A second useful word is منذ
It means "since" and "ago"

examples:

هي هنا منذ شهر
she has been here for a month/since one month
كانت هنا منذ شهر
she was here a month ago.

The different meanings above come because the first is in the present, implying that the state is continuing. She was there since one month, and still is there, and may stay longer even. The second one is in the past and finished so it means she was there one month ago.

To make a "continuous past" - something like "he was going" "she was doing", ie something fitting in the pattern

so & so was ....ing

you use kaana + a present tense (imperfect) verb.

Some examples:

كان يدرس
he was studying
كانت تطبخ
she was cooking
كنا نذهب الى المسجد
we were going to the masjid

It can also indicate a habitual action like:
كان يقرأ في المساء دائما

he always used to read in the evening

This construction can also be used in the negative like this:

لم يكن يكتب
he was not writing

exercises:

translate the following into Arabic:

1. Maryam has lived in Jordan for ten years
2. Moosa will come to London soon insha Allah
3. Ali was studying in Paris previously
4. Sufyan was sad for a long time.
5. Hasan has been happy since he got married
6. Tariq is working in the airport since last year
7. We used to always eat in the living room
8. He was not looking at the cat
9. The girls were talking
10. The children were playing in the street