First of all Filezilla is an FTP/SFTP client/server. We will need to use the client for this purpose.
1) Download the client from the URL: https://filezilla-project.org/
2) Go to AWS management console and then EC2. Select the instance that you want to access and then copy the DNS or IP address of the instance and then paste it in Filezilla host name.
Follow Image: Amazon Instance Access via FileZilla
3) Then, enter the username for the instance that you have created, For Amazon-ami it will be ec2-user and for other OS it would be different. Then, enter the password and port which will be 21 or 22.
4) Then, it will ask for the key, which is in pem format just select the .pem file and then it will confirm authentication. Click on Yes and then you are Done.
Note: In your EC2 Security group allow port number 21 and 22 whichever required for FTP access.