Unable to sign in my IMAP acount

Avijit24260 Hello, check out these pages for step-by-step guidance.

Add a Gmail account to Outlook
https://support.office.com/en-us/article/add-a-gmail-account-to-outlook-70191667-9c52-4581-990e-e30318c2c081 

Check Gmail through other email platforms
https://support.google.com/mail/answer/7126229?hl=en