Getting a job
When Paul left school he applied for (= wrote an official request for) a job in the accounts department of a local engineering company. They gave him a job as a trainee (= a very junior person in a company). He didn’t earn very much but they gave him a lot of training (= organised help and advice with learning the job), and sent him on training courses.
Note: Training is an uncountable noun, so you cannot say ‘a training’. You can only talk about training (in general), or a training course (if you want to refer to just one). Here you can use the verbs do or go on: I did / went on several training courses last year.
Paul worked hard at the company and his prospects (= future possibilities in the job) looked good. After his first year he got a good pay rise (= more money), and after two years he was promoted (= given a higher position with more money and responsibility). After six years he was in charge of (= responsible for / the boss of) the accounts department with five other employees (= workers in the company) under him (= under his responsibility/authority).
Leaving the company
By the time Paul was 30, however, he decided he wanted a fresh challenge (= a new exciting situation). He was keen to work abroad, so he resigned from his company (= officially told the company he was leaving his job; you can also say ‘he quit the company’) and started looking for a new job with a bigger company. After a couple of months he managed to find a job with an international company which involved (= included) a lot of foreign travel. He was very excited about the new job and at first he really enjoyed the travelling, but …
After about six months, Paul started to dislike the ~ constant moving around, and after a year he hated it; he hated living in hotels, and he never really made any friends in the new company. Unfortunately his work was not satisfactory either and finally he was sacked (= told to leave the company / dismissed / given the sack) a year later.
After that, Paul found things much more difficult. He was unemployed (- out of work / without a job) for over a year. He had to sell his car and move out of his new house. Things were looking bad and in the end Paul had to accept a part-time job (= working only some of the day or some of the week) on a fruit and vegetable stall in a market.
To his surprise, Paul loved the market. He made lots of friends and enjoyed working out in the open air. After two years, he took over (= took control of) the stall. Two years later he opened a second stall, and after ten years he had fifteen stalls. Last year Paul retired (= stopped working completely) at the age of 55, a very rich man.