Hi I ve just written by myself. Pls correct for me
AFTER I LEFT UNIVERSITY IN 2017 BECAUSE I DON'T LIKE MY MAYOR IN CHEMICAL ENGERNEERING. I DECIDIED TO TAKE GAP YEAR TO FIND OUT WHAT MAYOR I LIKE. IN MARCH 2019 I TOOK A ENGLISH CLASS TILL NOW TO IMPROVE MY ENGLISH SKILL AND SUPPORT FOR MY FUTURE CAREER SO I STILL HAVEN'T APPLIED FOR ANY JOB YET

Question

Hi I ve just written by myself. Pls correct for me
AFTER I LEFT UNIVERSITY IN 2017 BECAUSE I DON'T LIKE MY  MAYOR IN CHEMICAL ENGERNEERING. I DECIDIED TO TAKE GAP YEAR TO FIND OUT WHAT MAYOR I LIKE. IN MARCH 2019 I TOOK A ENGLISH CLASS  TILL NOW TO IMPROVE MY ENGLISH SKILL AND SUPPORT FOR MY FUTURE CAREER SO I STILL HAVEN'T APPLIED FOR ANY JOB YET

Answer

An excellent effort using some complex and compound sentences! 
Here are a few more suggestions.

In 2017, when I left university because I didn't like majoring in chemical engineering, I decided to take a gap year to discover which major I preferred. Since March 2019, I have been taking English classes to improve my English skills and support my future career in which I have not yet found employment.

Hope this helps

Answer

AFTER I LEFT UNIVERSITY IN 2017 BECAUSE I DON'T LIKE MY MAYOR IN CHEMICAL ENGERNEERING. I DECIDIED TO TAKE GAP YEAR TO FIND OUT WHAT MAYOR I LIKE. IN MARCH 2019 I TOOK A ENGLISH CLASS TILL NOW TO IMPROVE MY ENGLISH SKILL AND SUPPORT FOR MY FUTURE CAREER SO I STILL HAVEN'T APPLIED FOR ANY JOB YET

Corrected version:
After I left university in 2017 because I DIDN'T like my MAJOR in chemical engineering, I decided to take A gap year to find out what MAJOR I like. In March 2019, I took AN English class UNTIL now to improve my English skill and SUPPORT MY future career so I still haven't applied for A job yet.

Answer

Can I write it in any better way?

Verpassen Sie nicht die Gelegenheit, bequem von zu Hause aus eine Sprache zu lernen. Stöbern Sie in unserer Auswahl an erfahrenen Sprachlehrern und melden Sie sich jetzt zu Ihrer ersten Unterrichtsstunde an!