I have adhd is there anyone who can help improve my focus and concentration skills?

ADHD: yes. You need to make you sleep well at night 8-11 hour. You need to sleep around the same time everynight so your brain will turn off at night. You need to excercise for 45 minutes to one hour. Taking extra vitamin d and fish oil helps. Taking stimulant will help if you take with the above stuff I mentioned.

Refer to specialist: In addition to medication, there are techniques taught by educational specialists, neuropsychologists and speech and language specialists. I would start with a neuropsychologist to best understand the basis of your problems.