Are there any mistakes?

I have 6 months of /working/work/ experience in the field of recycling recycle. I have done research /about/on/ football spectators. I did a lot of advertising campaigns in various sectors.

I have experience in the fields of football and basketball. I /had/held [şimdi sahip olmuyor musunuz? Veya 'I hold'?] football and basketball licences. I was the first in an interprovincial football competition. /Therefore/So/, I started to educate some children who are willing wanted to learn football. Additionally, I go to a gym center for fitness /training/ four days a week in a regular way [daha doğal: 'on a regular basis']. As I have been taking fitness courses for a long time, . I have been given a training certificate [trainer's certificate?].

I have 6 months of working experience in the field of recycling. I have done research about football spectators. I did a lot of advertising campaigns in various sectors.

I have experience in the fields of football and basketball. I had football and basketball licences. I was first in an interprovincial football competition. Therefore, I started to educate some children who wanted to learn football. Additionally, I go to a gym center for fitness training four days a week on a regular basis. As I have been taking fitness courses for a long time. I have been given a training certificate.