If you have cPanel for your hosting, it is quite easy to create a new FTP account.
You may contact the support of your web host for access to your cPanel account.
Once you are in the cPanel account dashboard, click on "FTP Accounts". Refer to the screenshot below:
You will see a form as shown below to create a new FTP account.
Enter the FTP login username and password of your choice.
Notice the Directory in the above screenshot. Make sure you remove the default values populated by CPanel so that the input box is empty. Now, this particular FTP account will have access to all folders in the directory "/home/mysite/".
Click on Create FTP Account.
Once the FTP account is created, scroll down and you can see other details related to the newly created FTP account like seen in the sample screenshot below: