Come back :)

I haven't been here for a long time. I have started another course on at my university.. It is the MA course. Besides I have worked as a promotor for Sony. I sale laptops and tablets.

Come back :)

I haven't been here long time. I have started another course on my university.. It is MA course. Besides I have worked as promotor for Sony. I sale laptops and tablets.

I haven't been here in a long time.  I have started another course at my university.  It is an MA course.  Besides, I am working as a promoter for Sony.  I sale laptops and tablets.

Come I'm Back :)

I haven't been here for a long time. I have started another course on at my university, an It is MA course. Besides In addition, I have worked as a promotor for Sony I sale selling laptops and tablets.

This is how I would write it:

I haven't been here for a long time. I have started another course at my university.. It is an MA course. Besides, I have worked as a promoter for Sony. I sell laptops and tablets.

sell (to sell) = sprzedać

sale = sprzedaż, oferta specjalna

Sell and sale are pronounced almost the same, so it is easy to confuse them.